⚠️ Warning: This is a draft ⚠️

This means it might contain formatting issues, incorrect code, conceptual problems, or other severe issues.

If you want to help to improve and eventually enable this page, please fork RosettaGit's repository and open a merge request on GitHub.

;Task: Sort an array of elements using the [[wp:Shell sort|Shell sort]] algorithm, a diminishing increment sort.

The Shell sort (also known as Shellsort or Shell's method) is named after its inventor, Donald Shell, who published the algorithm in 1959.

Shell sort is a sequence of interleaved insertion sorts based on an increment sequence. The increment size is reduced after each pass until the increment size is 1.

With an increment size of 1, the sort is a basic insertion sort, but by this time the data is guaranteed to be almost sorted, which is insertion sort's "best case".

Any sequence will sort the data as long as it ends in 1, but some work better than others.

Empirical studies have shown a geometric increment sequence with a ratio of about 2.2 work well in practice. [http://www.cs.princeton.edu/~rs/shell/]

Other good sequences are found at the [https://oeis.org/search?q=shell+sort On-Line Encyclopedia of Integer Sequences].

## 360 Assembly

{{trans|PL/I}} The program uses ASM structured macros and two ASSIST macros to keep the code as short as possible.

```*        Shell sort                24/06/2016
SHELLSRT CSECT
USING  SHELLSRT,R13       base register
B      72(R15)            skip savearea
DC     17F'0'             savearea
STM    R14,R12,12(R13)    prolog
ST     R13,4(R15)         "
ST     R15,8(R13)         "
LR     R13,R15            "
L      RK,N               incr=n
SRA    RK,1               incr=n/2
DO WHILE=(LTR,RK,P,RK)    do while(incr>0)
LA     RI,1(RK)             i=1+incr
DO WHILE=(C,RI,LE,N)        do i=1+incr to n
LR     RJ,RI                  j=i
LR     R1,RI                  i
SLA    R1,2                   .
L      RT,A-4(R1)             temp=a(i)
LR     R2,RK                  incr
LA     R2,1(R2)               r2=incr+1
LR     R3,RJ                  j
SR     R3,RK                  j-incr
SLA    R3,2                   *.
LA     R3,A-4(R3)             r3=@a(j-incr)
LR     R4,RK                  incr
SLA    R4,2                   r4=incr*4
LR     R5,RJ                  j
SLA    R5,2                   .
LA     R5,A-4(R5)             @a(j)
*        do while j-incr>=1 and a(j-incr)>temp
DO WHILE=(CR,RJ,GE,R2,AND,C,RT,LT,0(R3))
L      R0,0(R3)                 a(j-incr)
ST     R0,0(R5)                 a(j)=a(j-incr)
SR     RJ,RK                    j=j-incr
LR     R5,R3                    @a(j)
SR     R3,R4                    @a(j-incr)=@a(j-incr)-incr*4
ENDDO  ,                      end do
ST     RT,0(R5)               a(j)=temp
LA     RI,1(RI)               i=i+1
ENDDO  ,                    end do
IF     C,RK,EQ,=F'2'        if incr=2
LA     RK,1                   incr=1
ELSE   ,                    else
LR     R5,RK                  incr
M      R4,=F'5'               *5
D      R4,=F'11'              /11
LR     RK,R5                  incr=incr*5/11
ENDIF  ,                    end if
ENDDO  ,                  end do
LA     R3,PG              pgi=0
LA     RI,1               i=1
DO     WHILE=(C,RI,LE,N)  do i=1 to n
LR     R1,RI                i
SLA    R1,2                 .
L      R2,A-4(R1)           a(i)
XDECO  R2,XDEC              edit a(i)
MVC    0(4,R3),XDEC+8       output a(i)
LA     R3,4(R3)             pgi=pgi+4
LA     RI,1(RI)             i=i+1
ENDDO  ,                  end do
XPRNT  PG,L'PG            print buffer
L      R13,4(0,R13)       epilog
LM     R14,R12,12(R13)    "
XR     R15,R15            "
BR     R14                exit
A     DC F'4',F'65',F'2',F'-31',F'0',F'99',F'2',F'83',F'782',F'1'
DC F'45',F'82',F'69',F'82',F'104',F'58',F'88',F'112',F'89',F'74'
N        DC     A((N-A)/L'A)       number of items of a
PG       DC     CL80' '            buffer
XDEC     DS     CL12               temp for xdeco
YREGS
RI       EQU    6                  i
RJ       EQU    7                  j
RK       EQU    8                  incr
RT       EQU    9                  temp
END    SHELLSRT
```

{{out}}

```
-31   0   1   2   2   4  45  58  65  69  74  82  82  83  88  89  99 104 112 782

```

## ActionScript

```function shellSort(data:Array):Array
{
var inc:uint = data.length/2;
while(inc > 0)
{
for(var i:uint = inc; i< data.length; i++)
{
var tmp:Object = data[i];
for(var j:uint = i; j >= inc && data[j-inc] > tmp; j -=inc)
{
data[j] = data[j-inc];
}
data[j] = tmp;
}
inc = Math.round(inc/2.2);
}
return data;
}

```

This is a generic implementation of the shell sort. Ada allows arrays to be indexed by integer or enumeration types starting at any value. This version deals with any kind or value of valid index type.

```generic
type Element_Type is digits <>;
type Index_Type is (<>);
type Array_Type is array(Index_Type range <>) of Element_Type;
package Shell_Sort is
procedure Sort(Item : in out Array_Type);
end Shell_Sort;
```
```package body Shell_Sort is

----------
-- Sort --
----------

procedure Sort (Item : in out Array_Type) is
Increment : Natural := Index_Type'Pos(Item'Last) / 2;
J : Index_Type;
Temp : Element_Type;
begin
while Increment > 0 loop
for I in Index_Type'Val(Increment) .. Item'Last loop
J := I;
Temp := Item(I);
while J > Index_Type'val(Increment) and then Item (Index_Type'Val(Index_Type'Pos(J) - Increment)) > Temp loop
Item(J) := Item (Index_Type'Val(Index_Type'Pos(J) - Increment));
J := Index_Type'Val(Index_Type'Pos(J) - Increment);
end loop;
Item(J) := Temp;
end loop;
if Increment = 2 then
Increment := 1;
else
Increment := Increment * 5 / 11;
end if;
end loop;
end Sort;

end Shell_Sort;
```

## ALGOL 68

{{trans|python}} {{works with|ALGOL 68|Revision 1 - one extension to language used - PRAGMA READ - a non standard feature similar to C's #include directive.}} {{works with|ELLA ALGOL 68|Any (with appropriate job cards) - tested with release 1.8.8d.fc9.i386}} {{works with|ALGOL 68G|Any - tested with release [http://sourceforge.net/projects/algol68/files/algol68g/algol68g-2.8 algol68g-2.8].}} '''File: prelude/sort/shell.a68'''

```# -*- coding: utf-8 -*- #

COMMENT
REQUIRES(
MODE SORTELEMENT = mode of element of array to be sorted...
OP < = (SORTELEMENT a, b)BOOL: a < b;
)
END COMMENT

MODE SORTELEMENTCMP = PROC(SORTELEMENT,SORTELEMENT)BOOL;

# create a global sort procedure for convenience #
PROC(SORTELEMENT,SORTELEMENT)BOOL sort cmp default := (SORTELEMENT a, b)BOOL: a < b;
PROC sort cmp rev = (SORTELEMENT a, b)BOOL: NOT sort cmp default(a,b);

# Alternative gap calculations: #
#     ⌊n/2**k⌋; ⌊n/2⌋; Θ(n**2) [when n=2**p]; Donald Shell 1959 #
PROC sort gap shell = (INT k, n)INT: n OVER 2;
#     2 ⌊n/2**(k+1)⌋+1; 2 ⌊n/4⌋+1, ..., 3, 1; Θ(n**(3/2)); Frank & Lazarus, 1960 #
#     2**k-1; 1, 3, 7, 15, 31, 63, ...; Θ(n**(3/2)); Hibbard, 1963 #
#     2**k+1, prefixed with 1; 1, 3, 5, 9, 17, 33, 65, ...; Θ(n**(3/2)); Papernov & Stasevich, 1965 #
#     successive numbers of the form 2**p 3**q; 1, 2, 3, 4, 6, 8, 9, 12, ...; Θ(n log**2 n); Pratt 1971 #
#     (3**k-1)/2, not greater than ⌈n/3⌉; 1, 4, 13, 40, 121, ...; Θ(n**(3/2)); Knuth 1973 #
#     ∏a[q], where r=⌊√(2k+√(2k))⌋ and a[q]=min(n∈𝒩:n≥(5/2)**(q+1) and ∀ p:0≤ p<q → gcd(a[p],n)=1);
limit where 0≤q<r and q≠(r**2+r)/2-k
1, 3, 7, 21, 48, 112, ...; O(n e**√(8ln(5/2)ln n)); Incerpi & Sedgewick, 1985 #
#     4**k+3×2**(k-1)+1, prefixed with 1; 1, 8, 23, 77, 281, ...; Θ(n**(4/3)); Sedgewick, 1986 #
#     9(4**(k-1)-2**(k-1))+1, 4**(k+1)-6×2**k+1; 1, 5, 19, 41, 109, ...; Θ(n**(4/3)); Sedgewick, 1986 #
#     h[k]=max(⌊5h[k-1]/11⌋, 1), h[0]=n; ⌊5N/11⌋, ⌊5/11 ⌊5N/11⌋⌋, ..., 1; Θ(?); Gonnet & Baeza-Yates, 1991 #
PROC sort gap gonnet and baeza yates = (INT k, n)INT: IF n=2 THEN 1 ELSE n*5 OVER 11 FI;
#     ⌈(9**k-4**k)/(5×4**(k-1))⌉; 1, 4, 9, 20, 46, 103, ...; Θ(?); Tokuda, 1992 #
#     unknown; 1, 4, 10, 23, 57, 132, 301, 701; Θ(?); Ciura, 2001 #

# set default gap calculation #
PROC (INT #k#, INT #n#)INT sort gap := sort gap gonnet and baeza yates;

PROC shell sort in place = (REF []SORTELEMENT array, UNION(VOID, SORTELEMENTCMP) opt cmp)REF[]SORTELEMENT:(
SORTELEMENTCMP cmp := (opt cmp|(SORTELEMENTCMP cmp): cmp | sort cmp default);
INT n := ( UPB array + LWB array + 1 ) OVER 2; # initial gap #
FOR k WHILE n NE 0 DO
FOR index FROM LWB array TO UPB array DO
INT i := index;
SORTELEMENT element = array[i];
WHILE ( i - LWB array >= n | cmp(element, array[i-n]) | FALSE ) DO
array[i] := array[i-n];
i -:= n
OD;
array[i] := element
OD;
n := sort gap(k,n)
OD;
array
);

PROC shell sort = ([]SORTELEMENT seq)[]SORTELEMENT:
shell sort in place(LOC[LWB seq: UPB seq]SORTELEMENT:=seq, EMPTY);

PROC shell sort rev = ([]SORTELEMENT seq)[]SORTELEMENT:
shell sort in place(LOC[LWB seq: UPB seq]SORTELEMENT:=seq, sort cmp rev);

SKIP
```

'''File: test/sort/shell.a68'''

```#!/usr/bin/a68g --script #
# -*- coding: utf-8 -*- #

MODE SORTELEMENT = CHAR;

[]SORTELEMENT char array data = "big fjords vex quick waltz nymph";
print((shell sort(char array data), new line))
```

{{out}}

```
abcdefghiijklmnopqrstuvwxyz

```

## ARM Assembly

{{works with|as|Raspberry Pi}}

```
/* ARM assembly Raspberry PI  */
/*  program shellSort.s   */

/************************************/
/* Constantes                       */
/************************************/
.equ STDOUT, 1     @ Linux output console
.equ EXIT,   1     @ Linux syscall
.equ WRITE,  4     @ Linux syscall
/*********************************/
/* Initialized data              */
/*********************************/
.data
szMessSortOk:       .asciz "Table sorted.\n"
szMessSortNok:      .asciz "Table not sorted !!!!!.\n"
sMessResult:        .ascii "Value  : "
sMessValeur:        .fill 11, 1, ' '            @ size => 11
szCarriageReturn:   .asciz "\n"

.align 4
iGraine:  .int 123456
.equ NBELEMENTS,      10
#TableNumber:      .int   1,3,6,2,5,9,10,8,4,7
TableNumber:     .int   10,9,8,7,6,5,4,3,2,1
/*********************************/
/* UnInitialized data            */
/*********************************/
.bss
/*********************************/
/*  code section                 */
/*********************************/
.text
.global main
main:                                             @ entry of program

1:
mov r1,#0                                     @ not use in routine
mov r2,#NBELEMENTS                            @ number of élements
bl shellSort
bl displayTable

mov r1,#NBELEMENTS                            @ number of élements
bl isSorted                                   @ control sort
cmp r0,#1                                     @ sorted ?
beq 2f
ldr r0,iAdrszMessSortNok                      @ no !! error sort
bl affichageMess
b 100f
2:                                                @ yes
bl affichageMess
100:                                              @ standard end of the program
mov r0, #0                                    @ return code
mov r7, #EXIT                                 @ request to exit program
svc #0                                        @ perform the system call

/******************************************************************/
/*     control sorted table                                   */
/******************************************************************/
/* r0 contains the address of table */
/* r1 contains the number of elements  > 0  */
/* r0 return 0  if not sorted   1  if sorted */
isSorted:
push {r2-r4,lr}                                    @ save registers
mov r2,#0
ldr r4,[r0,r2,lsl #2]
1:
cmp r2,r1
movge r0,#1
bge 100f
ldr r3,[r0,r2, lsl #2]
cmp r3,r4
movlt r0,#0
blt 100f
mov r4,r3
b 1b
100:
pop {r2-r4,lr}
bx lr                                              @ return
/***************************************************/
/*   shell Sort                                    */
/***************************************************/

/* r0 contains the address of table */
/* r1 contains the first element but not use !!   */
/*   this routine use first element at index zero !!!  */
/* r2 contains the number of element */
shellSort:
push {r0-r7,lr}              @save registers

sub r2,#1                    @ index last item
mov r1,r2                    @ init gap = last item
1:                               @ start loop 1
lsrs r1,#1                   @ gap = gap / 2
beq 100f                     @ if gap = 0 -> end
mov r3,r1                    @ init loop indice 1
2:                               @ start loop 2
ldr r4,[r0,r3,lsl #2]        @ load first value
mov r5,r3                    @ init loop indice 2
3:                               @ start loop 3
cmp r5,r1                    @ indice < gap
blt 4f                       @ yes -> end loop 2
sub r6,r5,r1                 @ index = indice - gap
ldr r7,[r0,r6,lsl #2]        @ load second value
cmp r4,r7                    @ compare values
strlt r7,[r0,r5,lsl #2]      @ store if <
sublt r5,r1                  @ indice = indice - gap
blt 3b                       @ and loop
4:                               @ end loop 3
str r4,[r0,r5,lsl #2]        @ store value 1 at indice 2
add r3,#1                    @ increment indice 1
cmp r3,r2                    @ end ?
ble 2b                       @ no -> loop 2
b 1b                         @ yes loop for new gap

100:                             @ end function
pop {r0-r7,lr}               @ restaur registers
bx lr                        @ return

/******************************************************************/
/*      Display table elements                                */
/******************************************************************/
/* r0 contains the address of table */
displayTable:
push {r0-r3,lr}                                    @ save registers
mov r3,#0
1:                                                     @ loop display table
ldr r0,[r2,r3,lsl #2]
bl conversion10                                    @ call function
bl affichageMess                                   @ display message
cmp r3,#NBELEMENTS - 1
ble 1b
bl affichageMess
100:
pop {r0-r3,lr}
bx lr
/******************************************************************/
/*     display text with size calculation                         */
/******************************************************************/
/* r0 contains the address of the message */
affichageMess:
push {r0,r1,r2,r7,lr}                          @ save  registres
mov r2,#0                                      @ counter length
1:                                                 @ loop length calculation
ldrb r1,[r0,r2]                                @ read octet start position + index
cmp r1,#0                                      @ if 0 its over
bne 1b                                         @ and loop
@ so here r2 contains the length of the message
mov r1,r0                                      @ address message in r1
mov r0,#STDOUT                                 @ code to write to the standard output Linux
mov r7, #WRITE                                 @ code call system "write"
svc #0                                         @ call systeme
pop {r0,r1,r2,r7,lr}                           @ restaur des  2 registres */
bx lr                                          @ return
/******************************************************************/
/*     Converting a register to a decimal unsigned                */
/******************************************************************/
/* r0 contains value and r1 address area   */
/* r0 return size of result (no zero final in area) */
/* area size => 11 bytes          */
.equ LGZONECAL,   10
conversion10:
push {r1-r4,lr}                                 @ save registers
mov r3,r1
mov r2,#LGZONECAL

1:                                                  @ start loop
bl divisionpar10U                               @ unsigned  r0 <- dividende. quotient ->r0 reste -> r1
strb r1,[r3,r2]                                 @ store digit on area
cmp r0,#0                                       @ stop if quotient = 0
subne r2,#1                                     @ else previous position
bne 1b                                          @ and loop
@ and move digit from left of area
mov r4,#0
2:
ldrb r1,[r3,r2]
strb r1,[r3,r4]
cmp r2,#LGZONECAL
ble 2b
@ and move spaces in end on area
mov r0,r4                                         @ result length
mov r1,#' '                                       @ space
3:
strb r1,[r3,r4]                                   @ store space in area
cmp r4,#LGZONECAL
ble 3b                                            @ loop if r4 <= area size

100:
pop {r1-r4,lr}                                    @ restaur registres
bx lr                                             @return

/***************************************************/
/*   division par 10   unsigned                    */
/***************************************************/
/* r0 dividende   */
/* r0 quotient */
/* r1 remainder  */
divisionpar10U:
push {r2,r3,r4, lr}
mov r4,r0                                          @ save value
//mov r3,#0xCCCD                                   @ r3 <- magic_number lower  raspberry 3
//movt r3,#0xCCCC                                  @ r3 <- magic_number higter raspberry 3
ldr r3,iMagicNumber                                @ r3 <- magic_number    raspberry 1 2
umull r1, r2, r3, r0                               @ r1<- Lower32Bits(r1*r0) r2<- Upper32Bits(r1*r0)
mov r0, r2, LSR #3                                 @ r2 <- r2 >> shift 3
add r2,r0,r0, lsl #2                               @ r2 <- r0 * 5
sub r1,r4,r2, lsl #1                               @ r1 <- r4 - (r2 * 2)  = r4 - (r0 * 10)
pop {r2,r3,r4,lr}
bx lr                                              @ leave function
iMagicNumber:  	.int 0xCCCCCCCD

```

## AutoHotkey

ahk forum: [http://www.autohotkey.com/forum/viewtopic.php?t=44657&postdays=0&postorder=asc&start=131 discussion]

```MsgBox % ShellSort("")
MsgBox % ShellSort("xxx")
MsgBox % ShellSort("3,2,1")
MsgBox % ShellSort("dog,000000,xx,cat,pile,abcde,1,cat,zz,xx,z")
MsgBox % ShellSort("12,11,10,9,8,4,5,6,7,3,2,1,10,13,14,15,19,17,18,16,20,10")

ShellSort(var) {                         ; SORT COMMA SEPARATED LIST
StringSplit a, var, `,                ; make array (length = a0)
inc := a0
While inc:=round(inc/2.2)             ; geometric gap sequence
Loop % a0-inc {                    ; insertion sort:
i := A_Index+inc, t := a%i%, j := i, k := j-inc
While j > inc && a%k% > t
a%j% := a%k%, j := k, k -= inc
a%j% := t
}
Loop % a0                             ; construct string from sorted array
s .= "," . a%A_Index%
Return SubStr(s,2)                    ; drop leading comma
}
```

## AWK

{{trans|Fortran}}

```{
line[NR] = \$0
}
END { # sort it with shell sort
increment = int(NR / 2)
while ( increment > 0 ) {
for(i=increment+1; i <= NR; i++) {
j = i
temp = line[i]
while ( (j >= increment+1) && (line[j-increment] > temp) ) {
line[j] = line[j-increment]
j -= increment
}
line[j] = temp
}
if ( increment == 2 )
increment = 1
else
increment = int(increment*5/11)
}
#print it
for(i=1; i <= NR; i++) {
print line[i]
}
}
```

## BBC BASIC

Note that the array index is assumed to start at zero.

```      DIM test(9)
test() = 4, 65, 2, -31, 0, 99, 2, 83, 782, 1
PROCshellsort(test(), 10)
FOR i% = 0 TO 9
PRINT test(i%) ;
NEXT
PRINT
END

DEF PROCshellsort(a(), n%)
LOCAL h%, i%, j%, k
h% = n%
WHILE h%
IF h% = 2 h% = 1 ELSE h% DIV= 2.2
FOR i% = h% TO n% - 1
k = a(i%)
j% = i%
WHILE j% >= h% AND k < a(ABS(j% - h%))
a(j%) = a(j% - h%)
j% -= h%
ENDWHILE
a(j%) = k
NEXT
ENDWHILE
ENDPROC
```

{{out}}

```
-31         0         1         2         2         4        65        83        99       782

```

## BCPL

```GET "libhdr"

LET shellsort(v, upb) BE
{ LET m = 1
UNTIL m>upb DO m := m*3 + 1  // Find first suitable value in the
// series:  1, 4, 13, 40, 121, 364, ...
{ m := m/3
FOR i = m+1 TO upb DO
{ LET vi = v!i
LET j = i
{ LET k = j - m
IF k<=0 | v!k < vi BREAK
v!j := v!k
j := k
} REPEAT
v!j := vi
}
} REPEATUNTIL m=1
}

MANIFEST { upb = 10000  }

LET start() = VALOF
{ LET v = getvec(upb)

try("shell", shellsort, v, upb)

writes("*nEnd of test*n")
freevec(v)
RESULTIS 0
}

AND try(name, sortroutine, v, upb) BE
{ // delay, referencing the first and last elements of v
FOR i = 1 TO 50000 DO v!upb := v!1
writef("*nSetting %n words of data for %s sort*n", upb, name)
FOR i = 1 TO upb DO v!i := randno(10000)
writef("Entering %s sort routine*n", name)
sortroutine(v, upb)
writes("Sorting complete*n")
TEST sorted(v, upb)
THEN writes("The data is now sorted*n")
ELSE writef("### ERROR: %s sort does not work*n", name)
}

AND sorted(v, n) = VALOF
{ //FOR i = 1 TO n-1 UNLESS v!i<=v!(i+1) RESULTIS FALSE
RESULTIS TRUE
}
```

## C

```#include <stdio.h>

void shell_sort (int *a, int n) {
int h, i, j, t;
for (h = n; h /= 2;) {
for (i = h; i < n; i++) {
t = a[i];
for (j = i; j >= h && t < a[j - h]; j -= h) {
a[j] = a[j - h];
}
a[j] = t;
}
}
}

int main (int ac, char **av) {
int a[] = {4, 65, 2, -31, 0, 99, 2, 83, 782, 1};
int n = sizeof a / sizeof a[0];
int i;
for (i = 0; i < n; i++)
printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
shell_sort(a, n);
for (i = 0; i < n; i++)
printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
return 0;
}

```

{{out}}

```
4 65 2 -31 0 99 2 83 782 1
-31 0 1 2 2 4 65 83 99 782

```

## C++

```
#include <time.h>
#include <iostream>

//--------------------------------------------------------------------------------------------------
using namespace std;

//--------------------------------------------------------------------------------------------------
const int MAX = 126;
class shell
{
public:
shell()
{ _gap[0] = 1750; _gap[1] = 701; _gap[2] = 301; _gap[3] = 132; _gap[4] = 57; _gap[5] = 23; _gap[6] = 10; _gap[7] = 4; _gap[8] = 1; }

void sort( int* a, int count )
{
_cnt = count;
for( int x = 0; x < 9; x++ )
if( count > _gap[x] )
{ _idx = x; break; }

sortIt( a );
}

private:
void sortIt( int* arr )
{
bool sorted = false;
while( true )
{
sorted = true;
int st = 0;
for( int x = _gap[_idx]; x < _cnt; x += _gap[_idx] )
{
if( arr[st] > arr[x] )
{ swap( arr[st], arr[x] ); sorted = false; }
st = x;
}
if( ++_idx >= 8 ) _idx = 8;
if( sorted && _idx == 8 ) break;
}
}

void swap( int& a, int& b ) { int t = a; a = b; b = t; }

int _gap[9], _idx, _cnt;
};
//--------------------------------------------------------------------------------------------------
int main( int argc, char* argv[] )
{
srand( static_cast<unsigned int>( time( NULL ) ) ); int arr[MAX];
for( int x = 0; x < MAX; x++ )
arr[x] = rand() % MAX - rand() % MAX;

cout << " Before: \n
### ===
\n";
for( int x = 0; x < 7; x++ )
{
for( int a = 0; a < 18; a++ )
{ cout << arr[x * 18 + a] << " "; }
cout << endl;
}
cout << endl; shell s; s.sort( arr, MAX );

cout << " After: \n
### ==
\n";
for( int x = 0; x < 7; x++ )
{
for( int a = 0; a < 18; a++ )
{ cout << arr[x * 18 + a] << " "; }
cout << endl;
}
cout << endl << endl; return system( "pause" );
}
//--------------------------------------------------------------------------------------------------

```

{{out}}

```
Before:

### =

-28 64 51 96 24 -51 15 4 51 37 -28 64 -18 -45 63 -64 -75 16
32 -44 -26 -50 -30 94 -55 -60 51 -30 14 -16 -42 22 91 -85 100 -14
-35 20 -73 11 -65 53 -25 -21 -65 16 -36 35 -69 -16 -13 -21 -103 80
-51 40 2 -7 11 29 65 -28 63 -108 -45 -8 -11 73 -8 -34 41 -20
-55 -64 4 41 5 -13 37 -39 -11 20 -24 -62 30 -19 30 -17 -11 -15
104 -14 -35 14 5 20 58 -38 6 -41 -23 88 49 -7 -54 -40 10 6
-57 -77 -6 -72 122 23 -39 67 121 63 28 31 43 -33 -1 59 -5 -91

After:
======
-108 -103 -91 -85 -77 -75 -73 -72 -69 -65 -65 -64 -64 -62 -60 -57 -55 -55
-54 -51 -51 -50 -45 -45 -44 -42 -41 -40 -39 -39 -38 -36 -35 -35 -34 -33
-30 -30 -28 -28 -28 -26 -25 -24 -23 -21 -21 -20 -19 -18 -17 -16 -16 -15
-14 -14 -13 -13 -11 -11 -11 -8 -8 -7 -7 -6 -5 -1 2 4 4 5
5 6 6 10 11 11 14 14 15 16 16 20 20 20 22 23 24 28
29 30 30 31 32 35 37 37 40 41 41 43 49 51 51 51 53 58
59 63 63 63 64 64 65 67 73 80 88 91 94 96 100 104 121 122

```

## C#

<lang C sharp|C#> public static class ShellSorter { public static void Sort(IList list) where T : IComparable { int n = list.Count; int h = 1;

```    while (h < (n >> 1))
{
h = (h << 1) + 1;
}

while (h >= 1)
{
for (int i = h; i < n; i++)
{
int k = i - h;
for (int j = i; j >= h && list[j].CompareTo(list[k]) < 0; k -= h)
{
T temp = list[j];
list[j] = list[k];
list[k] = temp;
j = k;
}
}
h >>= 1;
}
}
```

}

```
{{out}}

```txt

Before:

### =

-28 64 51 96 24 -51 15 4 51 37 -28 64 -18 -45 63 -64 -75 16
32 -44 -26 -50 -30 94 -55 -60 51 -30 14 -16 -42 22 91 -85 100 -14
-35 20 -73 11 -65 53 -25 -21 -65 16 -36 35 -69 -16 -13 -21 -103 80
-51 40 2 -7 11 29 65 -28 63 -108 -45 -8 -11 73 -8 -34 41 -20
-55 -64 4 41 5 -13 37 -39 -11 20 -24 -62 30 -19 30 -17 -11 -15
104 -14 -35 14 5 20 58 -38 6 -41 -23 88 49 -7 -54 -40 10 6
-57 -77 -6 -72 122 23 -39 67 121 63 28 31 43 -33 -1 59 -5 -91

After:
======
-108 -103 -91 -85 -77 -75 -73 -72 -69 -65 -65 -64 -64 -62 -60 -57 -55 -55
-54 -51 -51 -50 -45 -45 -44 -42 -41 -40 -39 -39 -38 -36 -35 -35 -34 -33
-30 -30 -28 -28 -28 -26 -25 -24 -23 -21 -21 -20 -19 -18 -17 -16 -16 -15
-14 -14 -13 -13 -11 -11 -11 -8 -8 -7 -7 -6 -5 -1 2 4 4 5
5 6 6 10 11 11 14 14 15 16 16 20 20 20 22 23 24 28
29 30 30 31 32 35 37 37 40 41 41 43 49 51 51 51 53 58
59 63 63 63 64 64 65 67 73 80 88 91 94 96 100 104 121 122

```

## COBOL

### Complete Program

{{works with|IBM Enterprise COBOL for z/OS}} Should work in Cobol/2 too. Picture for array to be sorted is purely fictional, there's no boundary check - hence: be careful! Program will sort any array using standard EBCDIC sequence (won't work properly with signed packed variables). In addition to the "usual" array and array lenght parameters, you need to supply an area (initialized to low-values) to detail row-length and up to 10 sort keys defined as follows: start position (1 based), length and sequence (Ascending/Descending).

```      *******************************************************
IDENTIFICATION DIVISION.
*******************************************************
PROGRAM-ID.      SHELLSRT.
************************************************************
*** SHELLSORT                                           ****
************************************************************
ENVIRONMENT DIVISION.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 II                        PIC S9(008) COMP-5.
01 IJ                        PIC S9(008) COMP-5.
01 IZ                        PIC S9(008) COMP-5.
01 IA                        PIC S9(008) COMP-5.
01 STRT1                     PIC S9(008) COMP-5.
01 STRT2                     PIC S9(008) COMP-5.
01 LGT                       PIC S9(008) COMP-5.
01 ORG                       PIC S9(008) COMP-5.
01 DST                       PIC S9(008) COMP-5.
*
01 GAP                       PIC S9(008) COMP-5.
01 NEGAP                     PIC S9(008) COMP-5.
01 TEMP                      PIC X(32768).
77 KEY-RESULT                PIC X.
*
01 SRT-ARRAY                 PIC  X(1000000).
01 NUM-ITEM                  PIC  9(008) COMP-5.
01 SRT-DATA.
03 LGT-ITEM               PIC  9(004) COMP-5.
03 SRT-KEYS.
05 SRT-KEY OCCURS 10.
07 K-START         PIC S9(004) COMP-5.
07 K-LENGTH        PIC S9(004) COMP-5.
07 K-ASC           PIC X.
*
*    P R O C E D U R E      D I V I S I O N
*
PROCEDURE DIVISION USING SRT-ARRAY NUM-ITEM SRT-DATA.

COMPUTE GAP = NUM-ITEM / 2.
PERFORM UNTIL GAP < 1
COMPUTE NEGAP = GAP * -1
PERFORM VARYING II FROM GAP BY 1
UNTIL II GREATER  NUM-ITEM
MOVE ' ' TO KEY-RESULT
COMPUTE ORG = (II - 1) * LGT-ITEM + 1
MOVE SRT-ARRAY(ORG:LGT-ITEM) TO TEMP(1:LGT-ITEM)
PERFORM VARYING IJ FROM II BY NEGAP
UNTIL IJ NOT GREATER  GAP
OR (KEY-RESULT NOT EQUAL '<' AND ' ')
COMPUTE IA = IJ - GAP
IF IA < 1
MOVE 1 TO IA
END-IF
PERFORM COMPARE-KEYS
IF KEY-RESULT = '<'
COMPUTE ORG = (IA - 1) * LGT-ITEM + 1
COMPUTE DST = (IJ - 1) * LGT-ITEM + 1
MOVE SRT-ARRAY(ORG:LGT-ITEM)
TO SRT-ARRAY(DST:LGT-ITEM)
COMPUTE DST = (IA - 1) * LGT-ITEM + 1
MOVE TEMP(1:LGT-ITEM) TO SRT-ARRAY(DST:LGT-ITEM)
END-IF
END-PERFORM
END-PERFORM
IF GAP = 2
MOVE 1 TO GAP
ELSE
COMPUTE GAP = GAP / 2.2
END-IF
END-PERFORM.
GOBACK.
*
COMPARE-KEYS.
MOVE ' ' TO KEY-RESULT
PERFORM VARYING IZ FROM 1 BY 1
UNTIL IZ GREATER 10
OR (KEY-RESULT NOT EQUAL '=' AND ' ')
IF SRT-KEY(IZ) GREATER LOW-VALUES
COMPUTE STRT1 = (IJ - 1) * LGT-ITEM + K-START(IZ)
COMPUTE STRT2 = (IA - 1) * LGT-ITEM + K-START(IZ)
MOVE K-LENGTH(IZ) TO LGT
IF SRT-ARRAY(STRT1:LGT) > SRT-ARRAY(STRT2:LGT) AND
K-ASC(IZ) EQUAL 'A'
OR SRT-ARRAY(STRT1:LGT) < SRT-ARRAY(STRT2:LGT) AND
K-ASC(IZ) EQUAL 'D'
MOVE '>' TO KEY-RESULT
END-IF
IF SRT-ARRAY(STRT1:LGT) < SRT-ARRAY(STRT2:LGT) AND
K-ASC(IZ) EQUAL 'A'
OR SRT-ARRAY(STRT1:LGT) > SRT-ARRAY(STRT2:LGT) AND
K-ASC(IZ) EQUAL 'D'
MOVE '<' TO KEY-RESULT
END-IF
END-IF
END-PERFORM.
IF KEY-RESULT = ' '
MOVE '=' TO KEY-RESULT
END-IF.
```

### Sorting Process

This excerpt contains just enough of the procedure division to show the workings. See the example for the bubble sort for a more complete program.

```       C-PROCESS SECTION.
C-000.
DISPLAY "SORT STARTING".

DIVIDE WC-SIZE BY 2 GIVING WC-GAP.

PERFORM E-PROCESS-GAP UNTIL WC-GAP = 0.

DISPLAY "SORT FINISHED".

C-999.
EXIT.

E-PROCESS-GAP SECTION.
E-000.
PERFORM F-SELECTION VARYING WB-IX-1 FROM WC-GAP BY 1
UNTIL WB-IX-1 > WC-SIZE.

DIVIDE WC-GAP BY 2.2 GIVING WC-GAP.

E-999.
EXIT.

F-SELECTION SECTION.
F-000.
SET WB-IX-2            TO WB-IX-1.
MOVE WB-ENTRY(WB-IX-1) TO WC-TEMP.

SET WB-IX-3 TO WB-IX-2.
SET WB-IX-3 DOWN BY WC-GAP.
PERFORM G-PASS UNTIL WB-IX-2 NOT > WC-GAP
* The next line logically reads :
*                   or wb-entry(wb-ix-2 - wc-gap) not > wc-temp.
OR WB-ENTRY(WB-IX-3) NOT > WC-TEMP.

IF WB-IX-1 NOT = WB-IX-2
MOVE WC-TEMP TO WB-ENTRY(WB-IX-2).

F-999.
EXIT.

G-PASS SECTION.
* Note that WB-IX-3 is WC-GAP less than WB-IX-2.
* Logically this should be :
*    move wb-entry(wb-ix-2 - wc-gap) to wb-entry(wb-ix-2).
*    set wb-ix-2 down by wc-gap.
* Unfortunately wb-entry(wb-ix-2 - wc-gap) is not legal in C2 cobol
G-000.
MOVE WB-ENTRY(WB-IX-3) TO WB-ENTRY(WB-IX-2).
SET WB-IX-2            DOWN BY WC-GAP.
SET WB-IX-3            DOWN BY WC-GAP.

G-999.
EXIT.
```

## Common Lisp

```(defun gap-insertion-sort (array predicate gap)
(let ((length (length array)))
(if (< length 2) array
(do ((i 1 (1+ i))) ((eql i length) array)
(do ((x (aref array i))
(j i (- j gap)))
((or (< (- j gap) 0)
(not (funcall predicate x (aref array (1- j)))))
(setf (aref array j) x))
(setf (aref array j) (aref array (- j gap))))))))

(defconstant +gaps+
'(1750 701 301 132 57 23 10 4 1)
"The best sequence of gaps, according to Marcin Ciura.")

(defun shell-sort (array predicate &optional (gaps +gaps+))
(assert (eql 1 (car (last gaps))) (gaps)
"Last gap of ~w is not 1." gaps)
(dolist (gap gaps array)
(gap-insertion-sort array predicate gap)))
```

## D

```import std.stdio: writeln;

void shellSort(T)(T[] seq) pure nothrow {
int inc = seq.length / 2;
while (inc) {
foreach (ref i, el; seq) {
while (i >= inc && seq[i - inc] > el) {
seq[i] = seq[i - inc];
i -= inc;
}
seq[i] = el;
}
inc = (inc == 2) ? 1 : cast(int)(inc * 5.0 / 11);
}
}

void main() {
auto data = [22, 7, 2, -5, 8, 4];
shellSort(data);
writeln(data);
}
```

{{out}}

```[-5, 2, 4, 7, 8, 22]
```

## Delphi

```Procedure ShellSort(var buf:Array of Integer);
const
gaps:array[0..7] of Integer = (701, 301, 132, 57, 23, 10, 4, 1);

var
whichGap, i, j, n, gap, temp : Integer;

begin
n := high(buf);
for whichGap := 0 to high(gaps) do begin
gap := gaps[whichGap];
for i := gap to n do begin
temp := buf[i];

j := i;
while ( (j >= gap ) and ( (buf[j-gap] > dt) ) do begin
buf[j] := buf[j-gap];
dec(j, gap);
end;
buf[j] := temp;
end;
end;
end;
```

## E

{{trans|Python}}

```/** Shell sort (in-place) */
def shellSort(array) {
var inc := array.size() // 2
while (inc.aboveZero()) {
for var i => a in array {
while (i >= inc && (def b := array[i - inc]) > a) {
array[i] := b
i -= inc
}
array[i] := a
}
inc := if (inc <=> 2) { 1 } else { (inc * 5.0 / 11).floor() }
}
}
```

## Eiffel

Translated from pseudocode at [http://en.wikipedia.org/wiki/Shell_sort#Shell_sort_algorithm_in_pseudocode Wikipedia]

{{works with|EiffelStudio|6.6 (with provisional loop syntax)}}

This solution is shown in the routine `sort` of the class `MY_SORTED_SET`.

For a more complete explanation of the Eiffel sort examples, see [[Sorting algorithms/Bubble sort#Eiffel|Bubble sort]].

```class
MY_SORTED_SET [G -> COMPARABLE]
inherit
TWO_WAY_SORTED_SET [G]
redefine
sort
end
create
make

feature

sort
-- Shell sort
local
inc: INTEGER
j: INTEGER
l_value: like item
do
from
inc := (count.to_double / 2.0).rounded
until
inc <= 0
loop
across inc |..| (count - 1) as ii
loop
l_value := Current [ii.item + 1]
from
j := ii.item
until
j < inc or Current [j - inc + 1] <= l_value
loop
Current [j + 1] := Current [j - inc + 1]
j := j - inc
end
Current [j + 1] := l_value
end
inc := (inc.to_double / 2.2).rounded
end
end

end
```

## Elixir

```defmodule Sort do
def shell_sort(list) when length(list)<=1, do: list
def shell_sort(list), do: shell_sort(list, div(length(list),2))

defp shell_sort(list, inc) do
gb = Enum.with_index(list) |> Enum.group_by(fn {_,i} -> rem(i,inc) end)
wk = Enum.map(0..inc-1, fn i ->
Enum.map(gb[i], fn {x,_} -> x end) |> insert_sort([])
end)
|> merge
if sorted?(wk), do: wk, else: shell_sort( wk, max(trunc(inc / 2.2), 1) )
end

defp merge(lists) do
len = length(hd(lists))
Enum.map(lists, fn list -> if length(list)<len, do: list++[nil], else: list end)
|> List.zip
|> Enum.flat_map(fn tuple -> Tuple.to_list(tuple) end)
|> Enum.filter(&(&1))               # remove nil
end

defp sorted?(list) do
Enum.chunk(list,2,1) |> Enum.all?(fn [a,b] -> a <= b end)
end

defp insert_sort(list), do: insert_sort(list, [])

defp insert_sort([], sorted), do: sorted
defp insert_sort([h | t], sorted), do: insert_sort(t, insert(h, sorted))

defp insert(x, []), do: [x]
defp insert(x, sorted) when x < hd(sorted), do: [x | sorted]
defp insert(x, [h | t]), do: [h | insert(x, t)]
end

list = [0, 14, 11, 8, 13, 15, 5, 7, 16, 17, 1, 6, 12, 2, 10, 4, 19, 9, 18, 3]
IO.inspect Sort.shell_sort(list)
```

{{out}}

```
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]

```

## Euphoria

```function shell_sort(sequence s)
integer gap,j
object temp
gap = floor(length(s)/2)
while gap > 0 do
for i = gap to length(s) do
temp = s[i]
j=i-gap
while j >= 1 and compare(temp, s[j]) <= 0 do
s[j+gap]=s[j]
j -= gap
end while
s[j+gap] = temp
end for
gap = floor(gap/2)
end while
return s
end function

constant s = rand(repeat(1000,10))
puts(1,"Before: ")
? s
puts(1,"After:  ")
? shell_sort(s)
```

{{out}}

```Before: {501,49,558,719,991,246,500,98,925,398}
After:  {49,98,246,398,500,501,558,719,925,991}

```

## Forth

{{works with|GNU Forth}}

```defer less?   ' < is less?

: shell { array len -- }
1 begin dup len u<= while 2* 1+ repeat { gap }
begin gap 2 = if 1 else gap 5 11 */ then dup to gap while
len gap do
array i cells +
dup @ swap         ( temp last )
begin gap cells -
array over u<=
while 2dup @ less?
while dup gap cells + over @ swap !
repeat then
gap cells + !
loop
repeat ;

create array 8 , 1 , 4 , 2 , 10 , 3 , 7 , 9 , 6 , 5 ,

array 10 shell
array 10 cells dump
```

A version without local variables:

```defer precedes ' < is precedes

: (shell)                              ( a n h -- a n h)
over >r tuck                         ( a h n h)
?do                                  ( a h)
i swap >r                          ( a j        R: h)
2dup cells + @ -rot                ( k a j      R: h)
begin                              ( k a j      R: h)
dup r@ - dup >r 0< 0=            ( k a j f    R: h j-h)
while                              ( k a j      R: h j-h)
-rot over over r@ cells + @      ( j k a k v  R: h j-h)
precedes >r rot r>               ( k a j f    R: h j-h)
while                              ( k a j      R: h j-h)
over r@ cells + @ >r             ( k a j      R: h j-h a[j-h])
2dup cells + r> swap !           ( k a j      R: h j-h)
drop r>                          ( k a j'     R: h)
repeat then                        ( k a j      R: h j-h)
rot >r 2dup cells +                ( a j a[j]   R: h j-h k)
r> swap ! r> drop drop r>          ( a h)
loop r> swap
;
( a n --)
: shell dup begin dup 2 = if 2/ else 5 11 */ then dup while (shell) repeat drop 2drop ;

create array 8 , 1 , 4 , 2 , 10 , 3 , 7 , 9 , 6 , 5 ,

array 10 shell
array 10 cells dump
```

## Fortran

{{works with|Fortran|90 and later}}

```MODULE sort

CONTAINS

SUBROUTINE Shell_Sort(a)

IMPLICIT NONE
INTEGER :: i, j, increment
REAL :: temp
REAL, INTENT(in out) :: a(:)

increment = SIZE(a) / 2
DO WHILE (increment > 0)
DO i = increment+1, SIZE(a)
j = i
temp = a(i)
DO WHILE (j >= increment+1 .AND. a(j-increment) > temp)
a(j) = a(j-increment)
j = j - increment
END DO
a(j) = temp
END DO
IF (increment == 2) THEN
increment = 1
ELSE
increment = increment * 5 / 11
END IF
END DO

END SUBROUTINE Shell_Sort

END MODULE sort

PROGRAM Shellsort

USE sort

IMPLICIT NONE
REAL :: array(1000)

CALL RANDOM_SEED
CALL RANDOM_NUMBER(array)

WRITE (*,*) "Unsorted array"
WRITE (*,*) array
WRITE (*,*)
CALL Shell_Sort(array)
WRITE (*,*) "Sorted array"
WRITE (*,*) array

END PROGRAM Shellsort
```

## FreeBASIC

modified bubble sort code

```' version 21-10-2016
' compile with: fbc -s console
' for boundry checks on array's compile with: fbc -s console -exx

Sub shellsort(s() As Long)
' sort from lower bound to the highter bound
' array's can have subscript range from -2147483648 to +2147483647
Dim As Long lb = LBound(s)
Dim As Long ub = UBound(s)
Dim As Long done, i, inc = ub - lb

Do
inc = Int(inc / 2.2)
If inc < 1 Then inc = 1

Do
done = 0
For i = lb To ub - inc
' replace "<" with ">" for downwards sort
If s(i) > s(i + inc) Then
Swap s(i), s(i + inc)
done = 1
End If
Next
Loop Until done = 0

Loop Until inc = 1

End Sub

' ------=< MAIN >=------

Dim As Long i, array(-7 To 7)

Dim As Long a = LBound(array), b = UBound(array)

Randomize Timer
For i = a To b : array(i) = i  : Next
For i = a To b ' little shuffle
Swap array(i), array(Int(Rnd * (b - a +1)) + a)
Next

Print "unsorted ";
For i = a To b : Print Using "####"; array(i); : Next : Print
shellsort(array())  ' sort the array
Print "  sorted ";
For i = a To b : Print Using "####"; array(i); : Next : Print

' empty keyboard buffer
While InKey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End
```

{{out}}

```unsorted    1  -4  -1   7  -6   3   6  -7  -5   2  -2   0   5   4  -3
sorted   -7  -6  -5  -4  -3  -2  -1   0   1   2   3   4   5   6   7
```

## Go

Following WP pseudocode:

```package main

import "fmt"

var a = []int{170, 45, 75, -90, -802, 24, 2, 66}

func main() {
fmt.Println("before:", a)
for inc := len(a) / 2; inc > 0; inc = (inc + 1) * 5 / 11 {
for i := inc; i < len(a); i++ {
j, temp := i, a[i]
for ; j >= inc && a[j-inc] > temp; j -= inc {
a[j] = a[j-inc]
}
a[j] = temp
}
}
fmt.Println("after: ", a)
}
```

{{out}}

```
before: [170 45 75 -90 -802 24 2 66]
after:  [-802 -90 2 24 45 66 75 170]

```

```import Data.List

shellSort xs = foldr (invColumnize (map (foldr insert []))) xs gaps
where gaps = takeWhile (< length xs) \$ iterate (succ.(3*)) 1
invColumnize f k = concat. transpose. f. transpose
. takeWhile (not.null). unfoldr (Just. splitAt k)
```

## Io

Translated from pseudocode at [[wp:Shell_sort#Shell_sort_algorithm_in_pseudocode|Wikipedia]]

```List do(
shellSortInPlace := method(
gap := (size / 2) round
while(gap > 0,
for(i, gap, size - 1,
key := at(i)
j := i

while(j >= gap and at(j - gap) > key,
atPut(j, at(j - gap))
j = j - gap
)
atPut(j, key)
)
gap = (gap / 2.2) round
)
self)
)

l := list(2, 3, 4, 5, 1)
l shellSortInPlace println # ==> list(1, 2, 3, 4, 5)
```

```procedure main()                     #: demonstrate various ways to sort a list and string
demosort(shellsort,[3, 14, 1, 5, 9, 2, 6, 3],"qwerty")
end

procedure shellsort(X,op)             #: return sorted X
local i,j,inc,temp

op := sortop(op,X)                 # select how and what we sort

inc := *X/2
while inc > 0 do {
every i := inc to *X do {
temp := X[j := i]
while op(temp,X[j - (j >= inc)]) do
X[j] := X[j -:= inc]
X[j] := temp
}
inc := if inc = 2 then 1 else inc*5/11 # switch to insertion near the end
}
return X
end
```

Note: This example relies on [[Sorting_algorithms/Bubble_sort#Icon| the supporting procedures 'sortop', and 'demosort' in Bubble Sort]]. The full demosort exercises the named sort of a list with op = "numeric", "string", ">>" (lexically gt, descending),">" (numerically gt, descending), a custom comparator, and also a string.

{{out}} Abbreviated sample

```Sorting Demo using procedure shellsort
on list : [ 3 14 1 5 9 2 6 3 ]
with op = &null:         [ 1 2 3 3 5 6 9 14 ]   (0 ms)
...
on string : "qwerty"
with op = &null:         "eqrtwy"   (0 ms)
```

=={{header|IS-BASIC}}== 100 PROGRAM "ShellSrt.bas" 110 RANDOMIZE 120 LET N=20 ! Number of elements 130 NUMERIC ARRAY(1 TO N) 140 CALL INIT(ARRAY) 150 CALL WRITE(ARRAY) 160 CALL SHELLSORT(ARRAY) 170 CALL WRITE(ARRAY) 180 DEF INIT(REF A) 190 FOR I=LBOUND(A) TO UBOUND(A) 200 LET A(I)=RND(N)+1 210 NEXT 220 END DEF 230 DEF WRITE(REF A) 240 FOR I=LBOUND(A) TO UBOUND(A) 250 PRINT A(I); 260 NEXT 270 PRINT 280 END DEF 290 DEF SHELLSORT(REF A) 300 LET D=2^INT(LOG(N)/LOG(2))-1 310 DO 320 LET I=1 330 DO WHILE I<=D AND I+D<=N 340 FOR J=I+D TO N STEP D 350 LET AH=A(J):LET BH=J-D 360 DO WHILE BH>0 AND AH<A(BH) 370 LET A(BH+D)=A(BH):LET BH=BH-D 380 LOOP 390 LET A(BH+D)=AH 400 NEXT 410 LET I=I+1 420 LOOP 430 LET D=INT(D/2) 440 LOOP WHILE D>0 450 END DEF

```

## J

{{eff note|J|/:~}}

'''Solution'''

```j
gaps      =: [: }: 1 (1+3*])^:(> {:)^:a:~ #
insert    =: (I.~ {. ]) , [ , ] }.~ I.~
gapinss   =: #@] {. ,@|:@(] insert//.~ #@] \$ i.@[)
shellSort =: [: ; gapinss &.>/@(< ,~ ]&.>@gaps)
```

Example:

```   shellSort 8 6 4 2 1 3 5 7 9
1 2 3 4 5 6 7 8 9
```

## Java

{{trans|Fortran}}

This method will sort in place. If you want to preserve your unsorted array, use a copy of the array as an argument to this method.

```public static void shell(int[] a) {
int increment = a.length / 2;
while (increment > 0) {
for (int i = increment; i < a.length; i++) {
int j = i;
int temp = a[i];
while (j >= increment && a[j - increment] > temp) {
a[j] = a[j - increment];
j = j - increment;
}
a[j] = temp;
}
if (increment == 2) {
increment = 1;
} else {
increment *= (5.0 / 11);
}
}
}
```

## JavaScript

```function shellSort (a) {
for (var h = a.length; h > 0; h = parseInt(h / 2)) {
for (var i = h; i < a.length; i++) {
var k = a[i];
for (var j = i; j >= h && k < a[j - h]; j -= h)
a[j] = a[j - h];
a[j] = k;
}
}
return a;
}

var a = [];
var n = location.href.match(/\?(\d+)|\$/)[1] || 10;
for (var i = 0; i < n; i++)
a.push(parseInt(Math.random() * 100));
shellSort(a);
document.write(a.join(" "));
```

## jq

shellSort as defined here can be used to sort an array of arbitrary JSON entities.

```# The "while" loops are implemented using the following jq function:

# As soon as "condition" is true, then emit . and stop:
def do_until(condition; next):
def u: if condition then . else (next|u) end;
u;

# sort the input array
def shellSort:
length as \$length
| [ (\$length/2|floor), .]                          # L1: state: [h, array]
| do_until( .[0] == 0;
.[0] as \$h
| reduce range(\$h; \$length) as \$i      # L2: state: array
( .[1];
.[\$i] as \$k
| [ \$i, . ]                       # L3: state: [j, array]
| do_until( .[0] < \$h or (\$k >= .[1][.[0] - \$h]);
.[0] as \$j
| [ (\$j - \$h), (.[1]|setpath([\$j]; .[\$j - \$h])) ] )
| .[0] as \$j | (.[1]|setpath([\$j]; \$k))  # i.e. a[j] = \$k
)
| [((\$h+1)*5/11 | floor), .] )
| .[1] ;
```

'''Example''':

```([],
[5,null,3,1,2,0,4.4,5]
) | shellSort
```

{{Out}}

```\$ jq -M -c -n -f Shell_sort.jq
[]
[null,0,1,2,3,4.4,5,5]
```

## Julia

{{trans|Java}}

```# v0.6

function shellsort!(a::Array{Int})::Array{Int}
incr = div(length(a), 2)
while incr > 0
for i in incr+1:length(a)
j = i
tmp = a[i]
while j > incr && a[j - incr] > tmp
a[j] = a[j-incr]
j -= incr
end
a[j] = tmp
end
if incr == 2
incr = 1
else
incr = floor(Int, incr * 5.0 / 11)
end
end
return a
end

x = rand(1:10, 10)
@show x shellsort!(x)
@assert issorted(x)
```

{{out}}

```x = [2, 6, 9, 2, 3, 9, 5, 2, 5, 9]
shellsort!(x) = [2, 2, 2, 3, 5, 5, 6, 9, 9, 9]
```

## Kotlin

```// version 1.1.0

val gaps = listOf(701, 301, 132, 57, 23, 10, 4, 1)  // Marcin Ciura's gap sequence

fun shellSort(a: IntArray) {
for (gap in gaps) {
for (i in gap until a.size) {
val temp = a[i]
var j = i
while (j >= gap && a[j - gap] > temp) {
a[j] = a[j - gap]
j -= gap
}
a[j] = temp
}
}
}

fun main(args: Array<String>) {
val aa = arrayOf(
intArrayOf(100, 2, 56, 200, -52, 3, 99, 33, 177, -199),
intArrayOf(4, 65, 2, -31, 0, 99, 2, 83, 782, 1),
intArrayOf(62, 83, 18, 53, 7, 17, 95, 86, 47, 69, 25, 28)
)
for (a in aa) {
shellSort(a)
println(a.joinToString(", "))
}
}
```

{{out}}

```
-199, -52, 2, 3, 33, 56, 99, 100, 177, 200
-31, 0, 1, 2, 2, 4, 65, 83, 99, 782
7, 17, 18, 25, 28, 47, 53, 62, 69, 83, 86, 95

```

## Liberty BASIC

```
siz = 100
dim a(siz)
for i = 1 to siz
a(i) = int(rnd(1) * 1000)
next

' -------------------------------
' Shell Sort
' -------------------------------
incr = int(siz / 2)
WHILE incr > 0
for i = 1 to siz
j    = i
temp = a(i)
WHILE (j >= incr+1 and a(abs(j-incr)) > temp)
a(j) = a(j-incr)
j    = j - incr
wend
a(j) = temp
next
IF incr = 2 THEN
incr = 1
ELSE
incr = int(incr * (5 / 11))
end if
WEND

for i = 1 to siz
print a(i)
next

```

## Lisaac

```Section Header

+ name := SHELL_SORT;

- external := `#include <time.h>`;

Section Public

- main <- (
+ a : ARRAY[INTEGER];

a := ARRAY[INTEGER].create 0 to 100;
`srand(time(NULL))`;
0.to 100 do { i : INTEGER;
a.put `rand()`:INTEGER to i;
};

shell a;

a.foreach { item : INTEGER;
item.print;
'\n'.print;
};
);

- shell a : ARRAY[INTEGER] <- (
+ lower, length, increment, temp : INTEGER;

lower := a.lower;
length := a.upper - lower + 1;
increment := length;
{
increment := increment / 2;
increment > 0
}.while_do {
increment.to (length - 1) do { i : INTEGER; + j : INTEGER;
temp := a.item(lower + i);
j := i - increment;
{ (j >= 0) && { a.item(lower + j) > temp } }.while_do {
a.put (a.item(lower + j)) to (lower + j + increment);
j := j - increment;
};
a.put temp to (lower + j + increment);
};
};
);
```

## Lua

```function shellsort( a )
local inc = math.ceil( #a / 2 )
while inc > 0 do
for i = inc, #a do
local tmp = a[i]
local j = i
while j > inc and a[j-inc] > tmp do
a[j] = a[j-inc]
j = j - inc
end
a[j] = tmp
end
inc = math.floor( 0.5 + inc / 2.2 )
end

return a
end

a = { -12, 3, 0, 4, 7, 4, 8, -5, 9 }
a = shellsort( a )

for _, i in pairs(a) do
print(i)
end
```

## M2000 Interpreter

{{trans|BBC BASIC}}

We use & for passing by reference. Variables with % are integers, and can be any type, a double by default with no decimals, or Decimal, Currency, Long, Integer, Float. When we change value, using operators ++ -- += -= /= *= the final value round to integer using 0.5 where 1.5 give 2. So A%=1/2 give A%=1 and A%=-1/2 give A%=-1. A%=Int(1/2) give A%=0, A%=Int(-1/2) give A%=-1 (int is same as floor() and there is ceil() too, and there is a Bank() for bank type rounding)

For Next in M2000 always execute at least one time the code inside (we can change it using a switch, in M2000 environment, to act as in BASIC). From step get the absolute value, and direction get from starting and ending value. So For i=1 to 0 { } execute two times the block with standard switch "-For" or no execute if switch is "+For". A For statement can be as in this example or the faster For { } without Next

```
Module ShellSortExample {
Module shellsort(&a()) {
DEf h%, i%, j%, k, n%
n%=LEN(a())
h% = n%
WHILE h% {
IF h% = 2  THEN {h% = 1 }ELSE h%= h% DIV 2.2
FOR i% = h% TO n% - 1
k = a(i%)
j% = i%
WHILE j% >= h% AND k < a(ABS(j% - h%)) {
a(j%) = a(j% - h%)
j% -= h%
}
a(j%) = k
NEXT i%
}
}

Dim numbers(10)
numbers(0)=4, 65, 2, -31, 0, 99, 2, 83, 782, 1
shellsort &numbers()
Print numbers()
}
ShellSortExample

```

## Maple

shellsort := proc(arr) local n, gap, i, val, j; n := numelems(arr): gap := trunc(n/2): while (gap > 0) do #notice by 1 error for i from gap to n by 1 do val := arr[i]; j := i; while (j > gap and arr[j-gap] > val) do arr[j] := arr[j-gap]; j -= gap; end do; arr[j] := val; end do; gap := trunc(gap/2); end do; end proc; arr := Array([17,3,72,0,36,2,3,8,40,0]); shellsort(arr); arr;

```
{{Out|Output}}

```txt
[0,0,2,3,3,8,17,36,40,72]
```

## Mathematica

```shellSort[ lst_ ] := Module[ {list = lst, incr, temp, i, j},
incr = Round[Length[list]/2];
While[incr > 0,

For[i = incr + 1, i <= Length[list], i++,

temp = list[[i]]; j = i;

While[(j >= (incr + 1)) && (list[[j - incr]] > temp) ,
list[[j]] = list[[j - incr]];  j = j-incr;
];

list[[j]] = temp;];
If[incr == 2, incr = 1, incr = Round[incr/2.2]]
];  list
]
```
```shellSort[{2,1,4,6,8}]
{1,2,4,6,8}
```

=={{header|MATLAB}} / {{header|Octave}}== This is a translation of the FORTRAN solution into MATLAB.

```function list = shellSort(list)

N = numel(list);
increment = round(N/2);

while increment > 0

for i = (increment+1:N)
temp = list(i);
j = i;
while (j >= increment+1) && (list(j-increment) > temp)
list(j) = list(j-increment);
j = j - increment;
end

list(j) = temp;

end %for

if increment == 2 %This case causes shell sort to become insertion sort
increment = 1;
else
increment = round(increment/2.2);
end
end %while
end %shellSort
```

Sample Usage:

``` shellSort([4 3 1 5 6 2])

ans =

1     2     3     4     5     6
```

## NetRexx

```/* NetRexx */
options replace format comments java crossref savelog symbols binary

placesList = [String -
"UK  London",     "US  New York",   "US  Boston",     "US  Washington" -
, "UK  Washington", "US  Birmingham", "UK  Birmingham", "UK  Boston"     -
]
sortedList = shellSort(String[] Arrays.copyOf(placesList, placesList.length))

lists = [placesList, sortedList]
loop ln = 0 to lists.length - 1
cl = lists[ln]
loop ct = 0 to cl.length - 1
say cl[ct]
end ct
say
end ln

return

method shellSort(a = String[]) public constant binary returns String[]

n = a.length
inc = int Math.round(double n / 2.0)
loop label inc while inc > 0
loop i_ = inc to n - 1
temp = a[i_]
j_ = i_
loop label j_ while j_ >= inc
if \(a[j_ - inc].compareTo(temp) > 0) then leave j_
a[j_] = a[j_ - inc]
j_ = j_ - inc
end j_
a[j_] = temp
end i_
inc = int Math.round(double inc / 2.2)
end inc

return a

method isTrue public constant binary returns boolean
return 1 == 1

method isFalse public constant binary returns boolean
return \isTrue

```

{{out}}

```
UK  London
US  New York
US  Boston
US  Washington
UK  Washington
US  Birmingham
UK  Birmingham
UK  Boston

UK  Birmingham
UK  Boston
UK  London
UK  Washington
US  Birmingham
US  Boston
US  New York
US  Washington

```

## Nim

```proc shellSort[T](a: var openarray[T]) =
var h = a.len
while h > 0:
h = h div 2
for i in h .. < a.len:
let k = a[i]
var j = i
while j >= h and k < a[j-h]:
a[j] = a[j-h]
j -= h
a[j] = k

var a = @[4, 65, 2, -31, 0, 99, 2, 83, 782]
shellSort a
echo a
```

## Objeck

{{trans|C sharp}}

```
bundle Default {
class ShellSort {
function : Main(args : String[]) ~ Nil {
a := [1, 3, 7, 21, 48, 112,336, 861, 1968, 4592, 13776,33936, 86961, 198768, 463792, 1391376,3402672, 8382192, 21479367, 49095696, 114556624,343669872, 52913488, 2085837936];
Shell(a);
each(i : a) {
IO.Console->Print(a[i])->Print(", ");
};
IO.Console->PrintLine();
}

function : native : Shell(a : Int[]) ~ Nil {
increment := a->Size() / 2;
while(increment > 0) {
for(i := increment; i < a->Size(); i += 1;) {
j := i;
temp := a[i];
while(j >= increment & a[j - increment] > temp) {
a[j] := a[j - increment];
j -= increment;
};
a[j] := temp;
};

if(increment = 2) {
increment := 1;
}
else {
increment *= (5.0 / 11);
};
};
}
}
}

```

## OCaml

{{trans|C}}

```let shellsort a =
let len = Array.length a in
let incSequence = [| 412771; 165103; 66041; 26417; 10567;
4231; 1693; 673; 269; 107; 43; 17; 7; 3; 1 |] in

Array.iter (fun increment ->
if (increment * 2) <= len then
for i = increment to pred len do
let temp = a.(i) in
let rec loop j =
if j < 0 || a.(j) <= temp then (j)
else begin
a.(j + increment) <- a.(j);
loop (j - increment)
end
in
let j = loop (i - increment) in
a.(j + increment) <- temp;
done;
) incSequence;
;;
```

and the main:

```let () =
let arraysize = 1000 in  (* or whatever *)
Random.self_init();
let intArray =
Array.init arraysize (fun _ -> Random.int 4000)
in
shellsort intArray;
Array.iter (Printf.printf " %d") intArray;
print_newline();
;;
```

## ooRexx

{{Trans|NetRexx}}

```/* Rexx */
-- --- Main --------------------------------------------------------------------
call demo
return
exit

-- -----------------------------------------------------------------------------
--  Shell sort implementation
-- -----------------------------------------------------------------------------
::routine shellSort
use arg ra

n = ra~items()
inc = format(n / 2.0,, 0) -- rounding
loop label inc while inc > 0
loop i_ = inc to n - 1
temp = ra~get(i_)
j_ = i_
loop label j_ while j_ >= inc
if \(ra~get(j_ - inc) > temp) then leave j_
ra~set(j_, ra~get(j_ - inc))
j_ = j_ - inc
end j_
ra~set(j_, temp)
end i_
inc = format(inc / 2.2,, 0) -- rounding
end inc

return ra

-- -----------------------------------------------------------------------------
-- Demonstrate the implementation
-- -----------------------------------------------------------------------------
::routine demo

placesList = .nlist~of( -
"UK  London",     "US  New York",   "US  Boston",     "US  Washington" -
, "UK  Washington", "US  Birmingham", "UK  Birmingham", "UK  Boston"     -
)

lists = .array~of( -
placesList -
, shellSort(placesList~copy()) -
)

loop ln = 1 to lists~items()
cl = lists[ln]
loop ct = 0 to cl~items() - 1
say right(ct + 1, 4)':' cl[ct]
end ct
say
end ln
return

-- -----------------------------------------------------------------------------
::routine isTrue
return 1 == 1

-- -----------------------------------------------------------------------------
::routine isFalse
return \isTrue()

-- -----------------------------------------------------------------------------
-- Helper class.  Map get and set methods for easier conversion from java.util.List
-- -----------------------------------------------------------------------------
::class NList mixinclass List public

-- Map get() to at()
::method get
use arg ix
return self~at(ix)

-- Map set() to put()
::method set
use arg ix, item
self~put(item, ix)
return

```

{{out}}

```
1: UK  London
2: US  New York
3: US  Boston
4: US  Washington
5: UK  Washington
6: US  Birmingham
7: UK  Birmingham
8: UK  Boston

1: UK  Birmingham
2: UK  Boston
3: UK  London
4: UK  Washington
5: US  Birmingham
6: US  Boston
7: US  New York
8: US  Washington

```

## PARI/GP

```shellSort(v)={
my(inc=#v\2);
while(inc,
for(i=inc+1,#v,
my(t=v[i],j=i);
while(j>inc && v[j-inc]>t,
v[j]=v[j-=inc]
);
v[j]=t
);
inc \= 2.2
);
v
};
```

## Pascal

```Const
MaxN = 100; { number of elements (my example is 100) }
Type
TArray = Array [0..MaxN] of Integer;

Procedure ShellSort ( var A : TArray; N : Integer );
Var
i, j, step, tmp : Integer;
Begin
step:=N div 2;  // step:=step shr 1
While step>0 Do Begin
For i:=step to N Do Begin
tmp:=A[i];
j:=i;
While (j>=step) and (A[j-step]>tmp) Do Begin
A[j]:=A[j-step];
dec(j,step);
End;
A[j]:=tmp;
End;
step:=step div 2;  // step:=step shr 1
End;
End;

```

## Perl

```sub shell_sort {
my (@a, \$h, \$i, \$j, \$k) = @_;
for (\$h = @a; \$h = int \$h / 2;) {
for \$i (\$h .. \$#a) {
\$k = \$a[\$i];
for (\$j = \$i; \$j >= \$h && \$k < \$a[\$j - \$h]; \$j -= \$h) {
\$a[\$j] = \$a[\$j - \$h];
}
\$a[\$j] = \$k;
}
}
@a;
}

my @a = map int rand 100, 1 .. \$ARGV[0] || 10;
say "@a";
@a = shell_sort @a;
say "@a";

```

## Perl 6

```sub shell_sort ( @a is copy ) {
loop ( my \$gap = (@a/2).round; \$gap > 0; \$gap = ( \$gap * 5 / 11 ).round ) {
for \$gap .. @a.end -> \$i {
my \$temp = @a[\$i];

my \$j;
loop ( \$j = \$i; \$j >= \$gap; \$j -= \$gap ) {
my \$v = @a[\$j - \$gap];
last if \$v <= \$temp;
@a[\$j] = \$v;
}

@a[\$j] = \$temp;
}
}
return @a;
}
my @data = 22, 7, 2, -5, 8, 4;
say 'input  = ' ~ @data;
say 'output = ' ~ @data.&shell_sort;

```

{{out}}

```
input  = 22 7 2 -5 8 4
output = -5 2 4 7 8 22

```

## Phix

Copy of [[Sorting_algorithms/Shell_sort#Euphoria|Euphoria]]

```function shell_sort(sequence s)
integer gap = floor(length(s)/2), j
object temp
while gap>0 do
for i=gap to length(s) do
temp = s[i]
j = i-gap
while j>=1 and temp<=s[j] do
s[j+gap] = s[j]
j -= gap
end while
s[j+gap] = temp
end for
gap = floor(gap/2)
end while
return s
end function
```

## PHP

```
function shellSort(\$arr)
{
\$inc = round(count(\$arr)/2);
while(\$inc > 0)
{
for(\$i = \$inc; \$i < count(\$arr);\$i++){
\$temp = \$arr[\$i];
\$j = \$i;
while(\$j >= \$inc && \$arr[\$j-\$inc] > \$temp)
{
\$arr[\$j] = \$arr[\$j - \$inc];
\$j -= \$inc;
}
\$arr[\$j] = \$temp;
}
\$inc = round(\$inc/2.2);
}
return \$arr;
}

```

## PL/I

```
/* Based on Rosetta Fortran */
Shell_Sort: PROCEDURE (A);
DECLARE A(*) FIXED;
DECLARE ( i, j, increment) FIXED BINARY (31);
DECLARE temp FIXED;

increment = DIMENSION(a) / 2;
DO WHILE (increment > 0);
DO i = lbound(A,1)+increment TO hbound(a,1);
j = i;
temp = a(i);
DO WHILE (j >= increment+1 & a(j-increment) > temp);
a(j) = a(j-increment);
j = j - increment;
END;
a(j) = temp;
END;
IF increment = 2 THEN
increment = 1;
ELSE
increment = increment * 5 / 11;
END;
END SHELL_SORT;

```

## PicoLisp

```(de shellSort (A)
(for (Inc (*/ (length A) 2)  (gt0 Inc)  (*/ Inc 10 22))
(for (I Inc  (get A I)  (inc I))
(let (Tmp @  J I)
(while (and (>= J Inc) (> (get A (- J Inc)) Tmp))
(set (nth A J) (get A (- J Inc)))
(dec 'J Inc) )
(set (nth A J) Tmp) ) ) )
A )
```

{{out}}

```: (shellSort (make (do 9 (link (rand 1 999)))))
-> (1 167 183 282 524 556 638 891 902)

: (shellSort (make (do 9 (link (rand 1 999)))))
-> (82 120 160 168 205 226 408 708 719)

: (shellSort (make (do 9 (link (rand 1 999)))))
-> (108 212 330 471 667 716 739 769 938)
```

## PowerShell

```Function ShellSort( [Array] \$data )
{
# http://oeis.org/A108870
\$A108870 = [Int64[]] ( 1, 4, 9, 20, 46, 103, 233, 525, 1182, 2660, 5985, 13467, 30301, 68178, 153401, 345152, 776591, 1747331, 3931496, 8845866, 19903198, 44782196, 100759940, 226709866, 510097200, 1147718700, 2582367076, 5810325920, 13073233321, 29414774973 )
\$datal = \$data.length - 1
\$inci = [Array]::BinarySearch( \$A108870, [Int64] ( [Math]::Floor( \$datal / 2 ) ) )
if( \$inci -lt 0 )
{
\$inci = ( \$inci -bxor -1 ) - 1
}
\$A108870[ \$inci..0 ] | ForEach-Object {
\$inc = \$_
\$_..\$datal | ForEach-Object {
\$temp = \$data[ \$_ ]
\$j = \$_
for( ; ( \$j -ge \$inc ) -and ( \$data[ \$j - \$inc ] -gt \$temp ); \$j -= \$inc )
{
\$data[ \$j ] = \$data[ \$j - \$inc ]
}
\$data[ \$j ] = \$temp
}
}
\$data
}

\$l = 10000; ShellSort( ( 1..\$l | ForEach-Object { \$Rand = New-Object Random }{ \$Rand.Next( 0, \$l - 1 ) } ) )
```

## PureBasic

{{trans|Fortran}}

```#STEP=2.2

Procedure Shell_sort(Array A(1))
Protected l=ArraySize(A()), increment=Int(l/#STEP)
Protected i, j, temp
While increment
For i= increment To l
j=i
temp=A(i)
While j>=increment And A(j-increment)>temp
A(j)=A(j-increment)
j-increment
Wend
A(j)=temp
Next i
If increment=2
increment=1
Else
increment*(5.0/11)
EndIf
Wend
EndProcedure
```

## Python

{{trans|Java}}

This method sorts in place. If you want to preserve your unsorted list, copy it first.

```

def shell(seq):
inc = len(seq) // 2
while inc:
for i, el in enumerate(seq):
while i >= inc and seq[i - inc] > el:
seq[i] = seq[i - inc]
i -= inc
seq[i] = el
inc = 1 if inc == 2 else int(inc * 5.0 / 11)

data = [22, 7, 2, -5, 8, 4]
shell(data)
print data # [-5, 2, 4, 7, 8, 22]
```

## Racket

```
#lang racket
(define (shell-sort! xs)
(define ref (curry vector-ref xs))
(define (new Δ) (if (= Δ 2) 1 (quotient (* Δ 5) 11)))
(let loop ([Δ (quotient (vector-length xs) 2)])
(unless (= Δ 0)
(for ([xᵢ (in-vector xs)] [i (in-naturals)])
(let while ([i i])
(cond [(and (>= i Δ) (> (ref (- i Δ)) xᵢ))
(vector-set! xs i (ref (- i Δ)))
(while (- i Δ))]
[else (vector-set! xs i xᵢ)])))
(loop (new Δ))))
xs)

```

## REXX

Historical data note: the three-character abbreviations were (and probably still are) the

official three-character abbreviations for the states of the USA before the advent of ZIP codes.

'''ZIP''' = '''Z'''one '''I'''mprovement '''P'''lan. Now-a-days, the USA uses two-character abbreviations.

```/*REXX program  sorts  a  stemmed array  using the  shell sort  (shellsort) algorithm.  */
call gen                                         /*generate the array elements.         */
call show           'before sort'                /*display the  before  array elements. */
say copies('▒', 75)                              /*displat a separator line  (a fence). */
call shellSort       #                           /*invoke the  shell  sort.             */
call show           ' after sort'                /*display the   after  array elements. */
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
gen:    @.=                                      /*assign a default value to stem array.*/
@.1='3 character abbreviations for states of the USA'       /*predates ZIP code.*/
@.2='
### =========================================
'
@.3='RHO  Rhode Island and Providence Plantations'    ;  @.36='NMX  New Mexico'
@.4='CAL  California'    ;   @.20='NEV  Nevada'       ;  @.37='IND  Indiana'
@.5='KAN  Kansas'        ;   @.21='TEX  Texas'        ;  @.38='MOE  Missouri'
@.6='MAS  Massachusetts' ;   @.22='VGI  Virginia'     ;  @.39='COL  Colorado'
@.7='WAS  Washington'    ;   @.23='OHI  Ohio'         ;  @.40='CON  Connecticut'
@.8='HAW  Hawaii'        ;   @.24='NHM  New Hampshire';  @.41='MON  Montana'
@.9='NCR  North Carolina';   @.25='MAE  Maine'        ;  @.42='LOU  Louisiana'
@.10='SCR  South Carolina';   @.26='MIC  Michigan'     ;  @.43='IOW  Iowa'
@.11='IDA  Idaho'         ;   @.27='MIN  Minnesota'    ;  @.44='ORE  Oregon'
@.12='NDK  North Dakota'  ;   @.28='MIS  Mississippi'  ;  @.45='ARK  Arkansas'
@.13='SDK  South Dakota'  ;   @.29='WIS  Wisconsin'    ;  @.46='ARZ  Arizona'
@.14='NEB  Nebraska'      ;   @.30='OKA  Oklahoma'     ;  @.47='UTH  Utah'
@.15='DEL  Delaware'      ;   @.31='ALA  Alabama'      ;  @.48='KTY  Kentucky'
@.16='PEN  Pennsylvania'  ;   @.32='FLA  Florida'      ;  @.49='WVG  West Virginia'
@.17='TEN  Tennessee'     ;   @.33='MLD  Maryland'     ;  @.50='NWJ  New Jersey'
@.18='GEO  Georgia'       ;   @.34='ALK  Alaska'       ;  @.51='NYK  New York'
@.19='VER  Vermont'       ;   @.35='ILL  Illinois'     ;  @.52='WYO  Wyoming'
do #=1  while @.#\==''; end;  #=#-1  /*determine number of entries in array.*/
return
/*──────────────────────────────────────────────────────────────────────────────────────*/
shellSort: procedure expose @.;   parse arg N    /*obtain the  N  from the argument list*/
i=N%2                                 /*%   is integer division in REXX.     */
do  while i\==0
do j=i+1  to N;    k=j;       p=k-i     /*P: previous item*/
_=@.j
do  while k>=i+1 & @.p>_;    @.k=@.p;   k=k-i;   p=k-i
end   /*while k≥i+1*/
@.k=_
end         /*j*/
if i==2  then i=1
else i=i * 5 % 11
end                  /*while i¬==0*/
return
/*──────────────────────────────────────────────────────────────────────────────────────*/
show:      do j=1  for #;  say 'element'  right(j,length(#)) arg(1)": "  @.j; end;  return
```

{{out|output|text= when using the (internal) inputs:}}

```element  1 before sort:  3 character abbreviations for states of the USA
element  2 before sort:
### =========================================

element  3 before sort:  RHO  Rhode Island and Providence Plantations
element  4 before sort:  CAL  California
element  5 before sort:  KAN  Kansas
element  6 before sort:  MAS  Massachusetts
element  7 before sort:  WAS  Washington
element  8 before sort:  HAW  Hawaii
element  9 before sort:  NCR  North Carolina
element 10 before sort:  SCR  South Carolina
element 11 before sort:  IDA  Idaho
element 12 before sort:  NDK  North Dakota
element 13 before sort:  SDK  South Dakota
element 14 before sort:  NEB  Nebraska
element 15 before sort:  DEL  Delaware
element 16 before sort:  PEN  Pennsylvania
element 17 before sort:  TEN  Tennessee
element 18 before sort:  GEO  Georgia
element 19 before sort:  VER  Vermont
element 20 before sort:  NEV  Nevada
element 21 before sort:  TEX  Texas
element 22 before sort:  VGI  Virginia
element 23 before sort:  OHI  Ohio
element 24 before sort:  NHM  New Hampshire
element 25 before sort:  MAE  Maine
element 26 before sort:  MIC  Michigan
element 27 before sort:  MIN  Minnesota
element 28 before sort:  MIS  Mississippi
element 29 before sort:  WIS  Wisconsin
element 30 before sort:  OKA  Oklahoma
element 31 before sort:  ALA  Alabama
element 32 before sort:  FLA  Florida
element 33 before sort:  MLD  Maryland
element 34 before sort:  ALK  Alaska
element 35 before sort:  ILL  Illinois
element 36 before sort:  NMX  New Mexico
element 37 before sort:  IND  Indiana
element 38 before sort:  MOE  Missouri
element 39 before sort:  COL  Colorado
element 40 before sort:  CON  Connecticut
element 41 before sort:  MON  Montana
element 42 before sort:  LOU  Louisiana
element 43 before sort:  IOW  Iowa
element 44 before sort:  ORE  Oregon
element 45 before sort:  ARK  Arkansas
element 46 before sort:  ARZ  Arizona
element 47 before sort:  UTH  Utah
element 48 before sort:  KTY  Kentucky
element 49 before sort:  WVG  West Virginia
element 50 before sort:  NWJ  New Jersey
element 51 before sort:  NYK  New York
element 52 before sort:  WYO  Wyoming
▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒
element  1  after sort:  3 character abbreviations for states of the USA
element  2  after sort:
### =========================================

element  3  after sort:  ALA  Alabama
element  4  after sort:  ALK  Alaska
element  5  after sort:  ARK  Arkansas
element  6  after sort:  ARZ  Arizona
element  7  after sort:  CAL  California
element  8  after sort:  COL  Colorado
element  9  after sort:  CON  Connecticut
element 10  after sort:  DEL  Delaware
element 11  after sort:  FLA  Florida
element 12  after sort:  GEO  Georgia
element 13  after sort:  HAW  Hawaii
element 14  after sort:  IDA  Idaho
element 15  after sort:  ILL  Illinois
element 16  after sort:  IND  Indiana
element 17  after sort:  IOW  Iowa
element 18  after sort:  KAN  Kansas
element 19  after sort:  KTY  Kentucky
element 20  after sort:  LOU  Louisiana
element 21  after sort:  MAE  Maine
element 22  after sort:  MAS  Massachusetts
element 23  after sort:  MIC  Michigan
element 24  after sort:  MIN  Minnesota
element 25  after sort:  MIS  Mississippi
element 26  after sort:  MLD  Maryland
element 27  after sort:  MOE  Missouri
element 28  after sort:  MON  Montana
element 29  after sort:  NCR  North Carolina
element 30  after sort:  NDK  North Dakota
element 31  after sort:  NEB  Nebraska
element 32  after sort:  NEV  Nevada
element 33  after sort:  NHM  New Hampshire
element 34  after sort:  NMX  New Mexico
element 35  after sort:  NWJ  New Jersey
element 36  after sort:  NYK  New York
element 37  after sort:  OHI  Ohio
element 38  after sort:  OKA  Oklahoma
element 39  after sort:  ORE  Oregon
element 40  after sort:  PEN  Pennsylvania
element 41  after sort:  RHO  Rhode Island and Providence Plantations
element 42  after sort:  SCR  South Carolina
element 43  after sort:  SDK  South Dakota
element 44  after sort:  TEN  Tennessee
element 45  after sort:  TEX  Texas
element 46  after sort:  UTH  Utah
element 47  after sort:  VER  Vermont
element 48  after sort:  VGI  Virginia
element 49  after sort:  WAS  Washington
element 50  after sort:  WIS  Wisconsin
element 51  after sort:  WVG  West Virginia
element 52  after sort:  WYO  Wyoming
───────────────────────────────────────────────────────────────────────────────

```

## Ring

```ring

aList = [-12, 3, 0, 4, 7, 4, 8, -5, 9]
shellSort(aList)
for i=1 to len(aList)
see "" + aList[i] + " "
next

func shellSort a
inc = ceil( len(a) / 2 )
while inc > 0
for i = inc to len(a)
tmp = a[i]
j = i
while j > inc and a[j-inc] > tmp
a[j] = a[j-inc]
j = j - inc
end
a[j] = tmp
next
inc = floor( 0.5 + inc / 2.2 )
end
return a

```

## Ruby

{{trans|Java}}

This method sorts in place. If you want to preserve your unsorted list, copy it first.

```ruby
class Array
def shellsort!
inc = length / 2
while inc != 0
inc.step(length-1) do |i|
el = self[i]
while i >= inc and self[i - inc] > el
self[i] = self[i - inc]
i -= inc
end
self[i] = el
end
inc = (inc == 2 ? 1 : (inc * 5.0 / 11).to_i)
end
self
end
end

data = [22, 7, 2, -5, 8, 4]
data.shellsort!
p data # [-5, 2, 4, 7, 8, 22]
```

## Run BASIC

```runbasic
siz = 100
dim a(siz)
for i = 1 to siz
a(i) = rnd(1) * 1000
next i

' -------------------------------
' Shell Sort
' -------------------------------
incr = int(siz / 2)
WHILE incr > 0
for i = 1 to siz
j    = i
temp = a(i)
WHILE (j >= incr and a(abs(j-incr)) > temp)
a(j) = a(j-incr)
j    = j - incr
WEND
a(j) = temp
next i
incr = int(incr / 2.2)
WEND
```

## Scala

```scala
object ShellSort {
def incSeq(len:Int)=new Iterator[Int]{
private[this] var x:Int=len/2
def hasNext=x>0
def next()={x=if (x==2) 1 else x*5/11; x}
}

def InsertionSort(a:Array[Int], inc:Int)={
for (i <- inc until a.length; temp=a(i)){
var j=i;
while (j>=inc && a(j-inc)>temp){
a(j)=a(j-inc)
j=j-inc
}
a(j)=temp
}
}

def shellSort(a:Array[Int])=for(inc<-incSeq(a.length)) InsertionSort(a, inc)

def main(args: Array[String]): Unit = {
var a=Array(2, 5, 3, 4, 3, 9, 3, 2, 5, 4, 1, 3, 22, 7, 2, -5, 8, 4)
println(a.mkString(","))
shellSort(a)
println(a.mkString(","))
}
}
```

{{out}}

```txt
2,5,3,4,3,9,3,2,5,4,1,3,22,7,2,-5,8,4
-5,1,2,2,2,3,3,3,3,4,4,4,5,5,7,8,9,22
```

## Seed7

```seed7
const proc: shellSort (inout array elemType: arr) is func
local
var integer: i is 0;
var integer: j is 0;
var integer: increment is 0;
var elemType: help is elemType.value;
begin
increment := length(arr) div 2;
while increment > 0 do
for i range 1 to length(arr) do
j := i;
help := arr[i];
while j > increment and arr[j - increment] > help do
arr[j] := arr[j - increment];
j -:= increment;
end while;
arr[j] := help;
end for;
increment := increment div 2;
end while;
end func;
```

Original source: [http://seed7.sourceforge.net/algorith/sorting.htm#shellSort]

## Sidef

{{trans|Perl}}

```ruby
func shell_sort(a) {
var h = a.len;
while (h >>= 1) {
for i in (h .. a.end) {
var k = a[i];
for (var j = i; (j >= h) && (k < a[j - h]); j -= h) {
a[j] = a[j - h];
}
a[j] = k;
}
}
return a;
}

var a = 10.of {100.irand};
say a;
shell_sort(a);
say a;
```

{{out}}

```txt
[54, 67, 65, 8, 56, 83, 64, 42, 20, 17]
[8, 17, 20, 42, 54, 56, 64, 65, 67, 83]
```

## Swift

{{works with|Swift|2.1}}

```swift>func shellsort 0 {
for (var i, el) in EnumerateSequence(seq) {
while i >= inc && seq[i - inc] > el {
seq[i] = seq[i - inc]
i -= inc
}
seq[i] = el
}
if inc == 2 {
inc = 1
} else {
inc = inc * 5 / 11
}
}
}
```

{{in}}

```txt
var data = [22, 7, 2, -5, 8, 4]
```

{{out}}

```txt
shellsort(&data) // [-5, 2, 4, 7, 8, 22]
```

## Tcl

```tcl
package require Tcl 8.5

proc shellsort {m} {
set len [llength \$m]
set inc [expr {\$len / 2}]
while {\$inc > 0} {
for {set i \$inc} {\$i < \$len} {incr i} {
set j \$i
set temp [lindex \$m \$i]
while {\$j >= \$inc && [set val [lindex \$m [expr {\$j - \$inc}]]] > \$temp} {
lset m \$j \$val
incr j -\$inc
}
lset m \$j \$temp
}
set inc [expr {\$inc == 2 ? 1 : \$inc * 5 / 11}]
}
return \$m
}

puts [shellsort {8 6 4 2 1 3 5 7 9}] ;# => 1 2 3 4 5 6 7 8 9
```

## uBasic/4tH

PRINT "Shell sort:"
n = FUNC (_InitArray)
PROC _ShowArray (n)
PROC _Shellsort (n)
PROC _ShowArray (n)
PRINT

END

_Shellsort PARAM (1)                   ' Shellsort subroutine
LOCAL (4)
b@ = a@

DO WHILE b@
b@ = b@ / 2
FOR c@ = b@ TO a@ - 1
e@ = @(c@)
d@ = c@
DO WHILE (d@ > b@-1) * (e@ < @(ABS(d@ - b@)))
@(d@) = @(d@ - b@)
d@ = d@ - b@
LOOP
@(d@) = e@
NEXT
LOOP
RETURN

_Swap PARAM(2)                         ' Swap two array elements
PUSH @(a@)
@(a@) = @(b@)
@(b@) = POP()
RETURN

_InitArray                             ' Init example array
PUSH 4, 65, 2, -31, 0, 99, 2, 83, 782, 1

FOR i = 0 TO 9
@(i) = POP()
NEXT

RETURN (i)

_ShowArray PARAM (1)                   ' Show array subroutine
FOR i = 0 TO a@-1
PRINT @(i),
NEXT

PRINT
RETURN
```

## Whitespace

[[/Whitespace|Implementation in Whitespace]].

## XPL0

```XPL0

include c:\cxpl\codes;          \intrinsic 'code' declarations
string 0;                       \use zero-terminated strings

proc    SSort(A, N);            \Shell sort array in ascending order
int     N;                      \number of elements in array (size)
int     I, J, Gap, JG, T;
[Gap:= N>>1;
while Gap > 0 do
[for I:= Gap to N-1 do
[J:= I - Gap;
loop    [JG:= J + Gap;
if A(J) <= A(JG) then quit;
T:= A(J);   A(J):= A(JG);   A(JG):= T;  \swap elements
J:= J - Gap;
if J < 0 then quit;
];
];
Gap:= Gap>>1;
];
];      \SSort

func    StrLen(Str);            \Return number of characters in an ASCIIZ string
char    Str;
int     I;
for I:= 0 to -1>>1-1 do
if Str(I) = 0 then return I;

char    Str;
[Str:= "Pack my box with five dozen liquor jugs.";
SSort(Str, StrLen(Str));
Text(0, Str);  CrLf(0);
]
```

{{out}}

```txt

"       .Pabcdeefghiiijklmnoooqrstuuvwxyz"

```

## Yabasic

```Yabasic
export sub shell_sort(x())
// Shell sort based on insertion sort

local gap, i, j, first, last, tempi, tempj

last = arraysize(x(),1)
gap = int(last / 10) + 1
while(TRUE)
first = gap + 1
for i = first to last
tempi = x(i)
j = i - gap
while(TRUE)
tempj = x(j)
if tempi >= tempj then
j = j + gap
break
end if
x(j+gap) = tempj
if j <= gap then
break
end if
j = j - gap
wend
x(j) = tempi
next i
if gap = 1 then
return
else
gap = int(gap / 3.5) + 1
end if
wend
end sub

if peek\$("library") = "main" then

clear screen

ITEMS = 100
dim numeros(ITEMS)

for n = 1 to ITEMS
numeros(n) = ran(ITEMS + 1)
next n

print time\$
shell_sort(numeros())
print time\$
print "Press a key to see ordered numbers."
inkey\$

for n = 1 to ITEMS
print numeros(n),", ";
next n

end if
```

## zkl

```zkl
// Shell sort a sequence of objects in place
// Requires mutiable list
fcn shellSort(sequence){
n := sequence.len();
gap := n / 2;
while (0 < gap){
i := gap;
while (i < n){
j := i - gap;
while ((j >= 0) and (sequence[j] > sequence[j + gap])){
sequence.swap(j,j + gap);
j -= gap;
}
i += 1;
}
gap /= 2;
}
return(sequence);
}
```

{{omit from|GUISS}}

```