⚠️ 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: Write a ''for'' loop which writes a countdown from '''10''' to '''0'''.

• [[Loop over multiple arrays simultaneously]]
• [[Loops/Break]]
• [[Loops/Continue]]
• [[Loops/Do-while]]
• [[Loops/Downward for]]
• [[Loops/For]]
• [[Loops/For with a specified step]]
• [[Loops/Foreach]]
• [[Loops/Increment loop index within loop body]]
• [[Loops/Infinite]]
• [[Loops/N plus one half]]
• [[Loops/Nested]]
• [[Loops/While]]
• [[Loops/with multiple ranges]]
• [[Loops/Wrong ranges]]

## 360 Assembly

Use of BXLE and BCT opcodes.

```*        Loops/Downward for        27/07/2015
LOOPDOWN CSECT
USING  LOOPDOWN,R12
LR     R12,R15            set base register
BEGIN    EQU    *
*        fisrt loop with a BXLE    BXLE: Branch on indeX Low or Equal
LH     R2,=H'11'          from 10 (R2=11) index
LH     R4,=H'-1'          step -1 (R4=-1)
LH     R5,=H'-1'          to 0    (R5=-1)
LOOPI    BXLE   R2,R4,ELOOPI       R2=R2+R4 if R2<=R5 goto ELOOPI
XDECO  R2,BUFFER          edit R2
XPRNT  BUFFER,L'BUFFER    print
B      LOOPI
ELOOPI   EQU    *
*        second loop with a BCT    BCT: Branch on CounT
LA     R2,10              index   R2=10
LA     R3,11              counter R3=11
LOOPJ    XDECO  R2,BUFFER          edit R2
XPRNT  BUFFER,L'BUFFER    print
BCTR   R2,0               R2=R2-1
ELOOPJ   BCT    R3,LOOPJ           R3=R3-1 if R3<>0 goto LOOPI
RETURN   XR     R15,R15            set return code
BUFFER   DC     CL80' '
YREGS
END    LOOPDOWN
```

## 6502 Assembly

Code is called as a subroutine (i.e. JSR Start). Printing routines are only partially coded here, specific OS/hardware routines for printing are left unimplemented.

```;An OS/hardware specific routine that is setup to display the Ascii character
;value contained in the Accumulator
Send 		= 	\$9000		;routine not implemented here
PrintNewLine	=	\$9050		;routine not implemented here

Start		PHA			;push Accumulator and Y register onto stack
TYA
PHA
LDY 	#10		;set Y register to loop start value
TYA			;place loop value in the Accumulator
Loop		JSR	PrintTwoDigits
JSR   PrintNewLine
DEY			;decrement loop value
BPL	Loop		;continue loop if sign flag is clear
PLA			;pop Y register and Accumulator off of stack
TAY
PLA
RTS			;exit

;Print value in Accumulator as two hex digits
PrintTwoDigits
PHA
LSR
LSR
LSR
LSR
JSR     PrintDigit
PLA
AND     #\$0F
JSR     PrintDigit
RTS

;Convert value in Accumulator to an Ascii hex digit
PrintDigit
ORA	#\$30
JSR	Send		;routine not implemented here
RTS
```

```for I in reverse 0..10 loop
Put_Line(Integer'Image(I));
end loop;
```

## Agena

Tested with Agena 2.9.5 Win32

```for i from 10 downto 0 do
print( i )
od
```

## ALGOL 60

'''Based on the 1962 Revised Repport on ALGOL''': '''begin''' '''integer''' i; '''for''' i:=10 '''step''' -1 '''until''' 0 '''do''' outinteger(i) '''end''' {{works with|ALGOL 60|OS/360}}

```'BEGIN' 'COMMENT' Loops/Downward for - Algol60 - 23/06/2018;
'INTEGER' I;
'FOR' I := 10 'STEP' -1 'UNTIL' 0 'DO'
OUTINTEGER(1,I)
'END'
```

## ALGOL 68

{{works with|ALGOL 68|Standard - no extensions to language used}} {{works with|ALGOL 68G|Any - tested with release mk15-0.8b.fc9.i386}} {{works with|ELLA ALGOL 68|Any (with appropriate job cards) - tested with release 1.8.8d.fc9.i386}}

```FOR i FROM 10 BY -1 TO 0 DO
print((i,new line))
OD
```

As a common extension the DOWNTO is sometimes included to optimise the loop termination logic. The DOWNTO is available in Marcel's [[ALGOL 68G]] and [[Cambridge ALGOL 68C]].

```FOR i FROM 10 DOWNTO 0 DO
print((i,new line))
OD
```

## ALGOL W

```begin
for i := 10 step -1 until 0 do
begin
write( i )
end
end.
```

## AmigaE

```PROC main()
DEF i
FOR i := 10 TO 0 STEP -1
WriteF('\d\n', i)
ENDFOR
ENDPROC
```

## AppleScript

```repeat with i from 10 to 0 by -1
log i
end repeat
```

## ARM Assembly

{{works with|as|Raspberry Pi}}

```

/* ARM assembly Raspberry PI  */
/*  program loopdownward.s   */

/* Constantes    */
.equ STDOUT, 1     @ Linux output console
.equ EXIT,   1     @ Linux syscall
.equ WRITE,  4     @ Linux syscall

/*********************************/
/* Initialized data              */
/*********************************/
.data
szMessResult:  .ascii "Counter = "      @ message result
sMessValeur:   .fill 12, 1, ' '
.asciz "\n"
/*********************************/
/* UnInitialized data            */
/*********************************/
.bss
/*********************************/
/*  code section                 */
/*********************************/
.text
.global main
main:                @ entry of program
push {fp,lr}      @ saves 2 registers
mov r4,#10
1:    @ begin loop
mov r0,r4
bl conversion10             @ call function with 2 parameter (r0,r1)
bl affichageMess            @ display message
subs r4,#1                   @ decrement counter
bge 1b                      @ loop if greather

100:   @ standard end of the program
mov r0, #0                  @ return code
pop {fp,lr}                 @restaur 2 registers
mov r7, #EXIT              @ request to exit program
svc #0                       @ perform the system call

/******************************************************************/
/*     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                                 */
/******************************************************************/
/* r0 contains value and r1 address area   */
conversion10:
push {r1-r4,lr}    @ save registers
mov r3,r1
mov r2,#10

1:	   @ start loop
bl divisionpar10 @ r0 <- dividende. quotient ->r0 reste -> r1
strb r1,[r3,r2]  @ store digit on area
sub r2,#1         @ previous position
cmp r0,#0         @ stop if quotient = 0 */
bne 1b	          @ else loop
@ and move spaces in first on area
mov r1,#' '   @ space
2:
strb r1,[r3,r2]  @ store space in area
subs r2,#1       @ @ previous position
bge 2b           @ loop if r2 >= zéro

100:
pop {r1-r4,lr}    @ restaur registres
bx lr	          @return
/***************************************************/
/*   division par 10   signé                       */
/* Thanks to http://thinkingeek.com/arm-assembler-raspberry-pi/*
/* and   http://www.hackersdelight.org/            */
/***************************************************/
/* r0 dividende   */
/* r0 quotient */
/* r1 remainder  */
divisionpar10:
/* r0 contains the argument to be divided by 10 */
push {r2-r4}   /* save registers  */
mov r4,r0
mov r3,#0x6667   @ r3 <- magic_number  lower
movt r3,#0x6666  @ r3 <- magic_number  upper
smull r1, r2, r3, r0   @ r1 <- Lower32Bits(r1*r0). r2 <- Upper32Bits(r1*r0)
mov r2, r2, ASR #2     /* r2 <- r2 >> 2 */
mov r1, r0, LSR #31    /* r1 <- r0 >> 31 */
add r0, r2, r1         /* r0 <- r2 + r1 */
add r2,r0,r0, lsl #2   /* r2 <- r0 * 5 */
sub r1,r4,r2, lsl #1   /* r1 <- r4 - (r2 * 2)  = r4 - (r0 * 10) */
pop {r2-r4}
bx lr                  /* leave function */

```

## Arturo

```loop \$(range 10 0) {
print &
}
```

{{out}}

```10
9
8
7
6
5
4
3
2
1
0
```

## AutoHotkey

```x := 10
While (x >= 0)
{
output .= "`n" . x
x--
}
MsgBox % output

```

## AWK

```BEGIN {
for(i=10; i>=0; i--) {
print i
}
}
```

## Axe

Axe does not support for loops with step sizes other than 1.

```For(I,0,10)
Disp 10-I▶Dec,i
End
```

## BASIC

```for i = 10 to 0 step -1
print i
next i
```

=

## Applesoft BASIC

=

```FOR I = 10 TO 0 STEP -1 : PRINT I : NEXT I
```

=

## BaCon

=

```' Downward for
FOR i = 10 DOWNTO 0 : PRINT i : NEXT
```

=

## Commodore BASIC

=

```10 FOR I = 10 TO 0 STEP -1
20 PRINT I
30 NEXT
```

==={{header|IS-BASIC}}=== 100 FOR I=10 TO 0 STEP-1 110 PRINT I 120 NEXT

```

## Batch File

```dos
@echo off
for /l %%D in (10,-1,0) do echo %%D
```

## BBC BASIC

```      FOR i% = 10 TO 0 STEP -1
PRINT i%
NEXT
```

## bc

```for (i = 10; i >= 0; i--) i
quit
```

```:.:v
@  ^ -1_
```

## Bracmat

```  10:?i
& whl'(out\$!i&!i+-1:~<0:?i)
```

## Brat

```10.to 0 { n | p n }
```

## C

```int i;
for(i = 10; i >= 0; --i)
printf("%d\n",i);
```

## C++

```for(int i = 10; i >= 0; --i)
std::cout << i << "\n";
```

## C#

```for (int i = 10; i >= 0; i--)
{
Console.WriteLine(i);
}
```

## Ceylon

```for (i in 10..0) {
print(i);
}
```

## Clojure

```(doseq [x (range 10 -1 -1)] (println x))
```

## COBOL

free-form

```identification division.
program-id. countdown.
environment division.
data division.
working-storage section.
01	counter 		pic 99.
88	counter-done	value 0.
01	counter-disp	pic Z9.
procedure division.
perform with test after varying counter from 10 by -1 until counter-done
move counter to counter-disp
display counter-disp
end-perform
stop run.
```

{{out}}

```10
9
8
7
6
5
4
3
2
1
0
```

## CoffeeScript

This could be written either in the array comprehension style, or in "regular" for loop style.

```# The more compact "array comprehension" style
console.log i for i in [10..0]

# The "regular" for loop style.
for i in [10..0]
console.log i

# More compact version of the above
for i in [10..0] then console.log i
```
```10
9
8
7
6
5
4
3
2
1
0
```

(the output is repeated three times; once for each loop)

## ColdFusion

With tags:

```<cfloop index = "i" from = "10" to = "0" step = "-1">
#i#
</cfloop>
```

With script:

```
for( i = 10; i <= 0; i-- )
{
writeOutput( i );
}
</cfscript>
```

## Common Lisp

```(loop for i from 10 downto 1 do
(print i))
```

## Chapel

```for i in 1..10 by -1 do
writeln(i);
```

In case you wonder why it is not written as 10..1 by -1: by is an operator that works on ranges, and it should work the same when the range was defined earlier, like in

```var r = 1..10;
for i in r by -1 do { ... }
```

## Clipper

```   FOR i := 10 TO 0 STEP -1
? i
NEXT
```

## D

```import std.stdio: writeln;

void main() {
for (int i = 10; i >= 0; --i)
writeln(i);
writeln();

foreach_reverse (i ; 0 .. 10 + 1)
writeln(i);
}
```

{{out}}

```10
9
8
7
6
5
4
3
2
1
0

10
9
8
7
6
5
4
3
2
1
0
```

## dc

does not use GNU extensions

[]s. is a comment

c clears the stack

[~...]p s. to print strings

lx executes the macro

uses the macro f - [p] to print, this can be replaced by any complex expressions.

```c

[macro s(swap) - (a b : b a)]s.
[Sa Sb La Lb] ss

[macro d(2dup) - (a b : a b a b)]s.
[Sa d Sb La d Lb lsx] sd

[macro m(for) - ]s.
[lfx 1 - ldx !<m ] sm

0 10 ldx [p] sf !<m
q
```

Using it

```|dc < ./for.dc
10
9
...
0
```

## Delphi

:''See [[#Pascal|Pascal]]''

## DWScript

```for i := 10 downto 0 do
PrintLn(i);
```

## E

```for i in (0..10).descending() { println(i) }
```

## EasyLang

for i = 10 downto 0 print i .

```

## EchoLisp

```scheme

(for ((longtemps-je-me-suis-couché-de-bonne-heure (in-range 10 -1 -1)))
(write longtemps-je-me-suis-couché-de-bonne-heure))
→ 10 9 8 7 6 5 4 3 2 1 0

```

## EDSAC order code

Including a full routine to print integers in decimal would probably be overkill; at least, it would obscure what is essentially a simple program. We therefore cheat slightly by printing "10\r\n" manually, and using the loop only to print "9\r\n" down to "0\r\n". Note that character codes are stored in the high 5 bits of the 17-bit EDSAC word: so we actually count down from 36,864 to 0 in steps of 4,096.

```[ Loop with downward counter

### ====================

A program for the EDSAC

Prints the integers 10 down to 0

The counter is stored at address 20@

Its initial value is 9 * 2^12
(9 in the high 5 bits, representing
the character '9') and it counts
down in steps of 2^12

Works with Initial Orders 2 ]

T56K    [ set load point ]
GK      [ set base address ]

[ orders ]

O14@    [ print figure shift ]
O15@    [ print '1' ]
O16@    [ print '0' ]
O17@    [ print CR ]
O18@    [ print LF ]

[ 5 ]   O20@    [ print c ]
O17@    [ print CR ]
O18@    [ print LF ]

T19@    [ acc := 0 ]
A20@    [ acc += c ]
S15@    [ acc -:= character '1' ]
U20@    [ c := acc ]

E5@     [ branch on non-negative ]

ZF      [ stop ]

[ constants ]

[ 14 ]  #F      [ πF -- figure shift ]
[ 15 ]  QF      [ character '1' ]
[ 16 ]  PF      [ character '0' ]
[ 17 ]  @F      [ θF -- CR ]
[ 18 ]  &F      [ ΔF -- LF ]

[ variables ]

[ 19 ]  P0F     [ used to clear acc ]
[ 20 ]  OF      [ character c = '9' ]

EZPF    [ start when loaded ]
```

## EGL

```for ( i int from 10 to 0 decrement by 1 )
SysLib.writeStdout( i );
end
```

## Elixir

```iex(1)> Enum.each(10..0, fn i -> IO.puts i end)
10
9
8
7
6
5
4
3
2
1
0
:ok
```

## Erlang

```%% Implemented by Arjun Sunel
-module(downward_loop).
-export([main/0]).

main() ->
for_loop(10).

for_loop(N) ->
if N > 0 ->
io:format("~p~n",[N] ),
for_loop(N-1);
true ->
io:format("~p~n",[N])
end.

```

{{out}}

```10
9
8
7
6
5
4
3
2
1
0
ok
```

## ERRE

```
FOR I%=10 TO 0 STEP -1 DO
PRINT(I%)
END FOR

```

## Euphoria

```for i = 10 to 0 by -1 do
? i
end for
```

## Ela

### Standard Approach

```open monad io

each [] = do return ()
each (x::xs) = do
putStrLn \$ show x
each xs

each [10,9..0] ::: IO
```

### Alternative Approach

```open monad io

countDown m n | n < m = do return ()
| else = do
putStrLn \$ show n
countDown m (n - 1)

_ = countDown 0 10 ::: IO
```

## Factor

``` [ . ] each
```

## FALSE

```10[\$0>][\$." "1-]#.
```

## Fantom

```
class DownwardFor
{
public static Void main ()
{
for (Int i := 10; i >= 0; i--)
{
echo (i)
}
}
}

```

## FBSL

```#APPTYPE CONSOLE

FOR DIM i = 10 DOWNTO 0
PRINT i
NEXT

PAUSE

```

## Forth

Unlike the incrementing 10 0 DO-LOOP, this will print eleven numbers. The LOOP words detect crossing the floor of the end limit.

```: loop-down  0 10 do  i .  -1 +loop ;
```

## Fortran

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

```DO i = 10, 0, -1
WRITE(*, *) i
END DO
```

{{works with|Fortran|77 and later}}

```      PROGRAM DOWNWARDFOR
C Initialize the loop parameters.
INTEGER I, START, FINISH, STEP
PARAMETER (START = 10, FINISH = 0, STEP = -1)

C If you were to leave off STEP, it would default to positive one.
DO 10 I = START, FINISH, STEP
WRITE (*,*) I
10   CONTINUE

STOP
END
```

## FreeBASIC

```' FB 1.05.0 Win64

For i As Integer = 10 To 0 Step -1
Print i; " ";
Next
Print
Sleep
```

{{out}}

```
10  9  8  7  6  5  4  3  2  1  0

```

## Frink

```
for i = 10 to 0 step -1
println[i]

```

```for i in 10..-1..0 do
printfn "%d" i
```

Using the 'downto' keyword:

```for i = 10 downto 0 do
printfn "%d" i
```

## FutureBasic

```
include "ConsoleWindow"

dim as long i

for i = 10 to 0 step -1
print i
next

```

Output:

```
10
9
8
7
6
5
4
3
2
1
0

```

## GAP

```for i in [10, 9 .. 0] do
Print(i, "\n");
od;
```

## GML

```for(i = 10; i >= 0; i -= 1)
show_message(string(i))
```

## Gambas

'''[https://gambas-playground.proko.eu/?gist=b236db5bdb1087fa90e934a5a8210e1f Click this link to run this code]'''

```Public Sub Main()
Dim siCount As Short

For siCount = 10 DownTo 0
Print siCount;;
Next

End
```

Output:

```
10 9 8 7 6 5 4 3 2 1 0

```

## Go

```= 0; i-- {
fmt.Println(i)
}
```

## Groovy

```for (i in (10..0)) {
println i
}
```

```
10 FOR I% = 10 TO 0 STEP -1
20  PRINT I%
30 NEXT I%

```

## Harbour

```FOR i := 10 TO 0 STEP -1
? i
NEXT
```

```import Control.Monad

main :: IO ()
main = forM_ [10,9 .. 0] print
```

## hexiscript

```= 0; i--
println i
endfor
```

## HicEst

```DO i = 10, 0, -1
WRITE() i
ENDDO
```

## HolyC

```I8 i;
for (i = 10; i >= 0; --i)
Print("%d\n", i);
```

## IDL

Using a loop (with an "increment of minus one" ):

```for i=10,0,-1 do print,i
```

But in IDL one would rarely use loops (for anything) since practically everything can be done with vectors/arrays.

The "IDL way of doing things" for the countdown requested in the task would probably be this:

```print,10-indgen(11)
```

=={{header|Icon}} and {{header|Unicon}}== There are four looping controls 'every', 'repeat', 'until', and 'while' (see [[Icon%2BUnicon/Intro#Looping_Controls|Introduction to Icon and Unicon/Looping Controls]] for more information.) The closest to a 'for' loop is 'every'.

```every i := 10 to 0 by -1 do {
# things to do within the loop
}

```

## Inform 6

```for(i = 10: i >= 0: i--)
print i, "^";
```

## Io

```for(i,10,0,-1,
i println
)
```

## J

J is array-oriented, so there is very little need for loops. For example, one could satisfy this task this way:

,. i. -11

J does support loops for those times they can't be avoided (just like many languages support gotos for those time they can't be avoided).

```3 : 0 ] 11
for_i. i. - y do.
smoutput i
end.
)
```

Though it's rare to see J code like this.

That said, a convenient routine for generating intervals in J might be:

```thru=: <. + i.@(+*)@-~
```

For example:

```   10 thru 0
10 9 8 7 6 5 4 3 2 1 0
```

(or `,.10 thru 0` if you want each number on a line by itself)

This verb "thru" will count up or down, starting and stop at the indicated left and right ending points.

## Java

```for(i = 10; i >= 0; --i){
System.out.println(i);
}
```

## JavaScript

```for (var i=10; i>=0; --i) print(i);
```

Alternatively, remaining for the moment within an imperative idiom of JavaScript, in which programs are composed of statements, we could trim the computational costs over longer reversed iterations by moving the mutation into the test, and dropping the third term of a for() statement:

```for (var i = 11; i--;) console.log(i);
```

and it sometimes might be more natural, especially at scales at which optimisation becomes an issue, to go one step further and express the same computation with the more economical while statement.

```var i = 11;
while (i--) console.log(i);
```

In a functional idiom of JavaScript, however, we need an expression with a value (which can be composed within superordinate expressions), rather than a statement, which produces a side-effect but returns no information-bearing value.

If we have grown over-attached to the English morpheme 'for', we might think first of turning to '''Array.forEach()''', and write something like:

```function range(m, n) {
return Array.apply(null, Array(n - m + 1)).map(
function (x, i) {
return m + i;
}
);
}

range(0, 10).reverse().forEach(
function (x) {
console.log(x);
}
);
```

but this is still a statement with side-effects, rather than a composable expression with a value.

We can get an expression (assuming that the range() function (above) is defined) but replacing Array.forEach with '''Array.map()'''

```console.log(
range(0, 10).reverse().map(
function (x) {
return x;
}
).join('\n')
);
```

but in this case, we are simply mapping an identity function over the values, so the expression simplifies down to:

```console.log(
range(0, 10).reverse().join('\n')
);
```

## jq

If range/3 is available in your jq:

```range(10;-1;-1)
```

Otherwise: range(-10;1) | -.

## Julia

```for i in 10:-1:0
println(i)
end
```

## Kotlin

```// version 1.0.6

fun main(args: Array<String>) {
for (i in 10 downTo 0) print("\$i ")
}
```

{{out}}

```
10 9 8 7 6 5 4 3 2 1 0

```

## Lasso

```loop(-from=10, -to=0, -by=-1) => {^ loop_count + ' ' ^}
```

## Lhogho

Slightly different syntax for `for` compared to Logo.

```for "i [10 0] [print :i]
```

## Liberty BASIC

```
for i = 10 to 0 step -1
print i
next i
end

```

## Lingo

```repeat with i = 10 down to 0
put i
end repeat
```

## Lisaac

```10.downto 0 do { i : INTEGER;
i.println;

};
```

## LiveCode

Livecode's repeat "for" variant does not have a "down to" form, in a function you would need to manually decrement a counter

```local x=10
repeat for 10 times
put x & return
end repeat
```

A more idiomatic approach using "with" variant of repeat which does have a "down to" form

```repeat with n=10 down to 1
put n
end repeat
```

If the limit is less than the start, then FOR decrements the control variable. Otherwise, a fourth parameter could be given as a custom increment.

```for [i 10 0] [print :i]
```

```
for i=10,0,-1 do
print(i)
end

```

## M2000 Interpreter

M2000 can operate a For like in BASIC or Like M2000. In M2000 mode, a For always execute at least one time the block inside. This FOR use absolute value of step, except when we have start value and end value the same value, so from sign of step, interpreter calculate the exit value.

We can change the iterator variable of a For, but this variable is a copy of actual iterator, and next step get the proper value. So we can't change the numbers of steps, but we can use continue to skip rest of code and execute next step, or exit to exit block and stop loop. Also we can use Goto to stop loop and continue from a label.

There is a slower For, the For Next style:

```
For i=1 to 10 step 2 : Print i : Next i

```

We have to use Exit For to exit from that type of For.

This is not an error (each for has private counter value):

for i=1 to 10 :for i=1 to 2:Print i:Next i:Next i

We get 10 times two values: 1 2

```
Form 80, 50
Module Checkit {
set switches "+For"
For i=10 to 1 step -1 {
Print i
}
Print i=0
\\ this For switch make it like For in BASIC
\\ block skipped
For i=1 to 10 step -1 {
Print i
}
print i=1
\\ but this is the default behavior
\\
set switches "-For"
\\ sign of step used when start is same as end to calculate the exit value of i
\\ This is the standard, and a For always execute at least one time the block.
\\ use absulute step_Value. Because 10>1 direction is downward.
For i=10 to 1 step -1 {
Print i
}
Print i=0
\\  loop from 1 to 10, using abs(step_value)
For i=1 to 10 step -1 {
Print i
}
print i=11
For i=1 to 1 step -1 {
Print i
}
Print i=0
}
CheckIt

```

## M4

```define(`for',
`ifelse(\$#,0,``\$0'',
`ifelse(eval(\$2 \$3),1,
`pushdef(`\$1',\$2)\$5`'popdef(`\$1')\$0(`\$1',eval(\$2+\$4),\$3,\$4,`\$5')')')')dnl

for(`x',`10',`>=0',`-1',`x
')
```

## Maple

Using an explicit loop:

```for i from 10 to 0 by -1 do print(i) end:
```

Pushing the loop into the kernel:

```seq(print(i),i=10..0,-1)
```

## Mathematica

Mathematica provides several ways to iterate over a range of numbers, small subtle differences are amongst them. 3 possible implementations are (exactly the same output):

Using For:

```For[i = 10, i >= 0, i--, Print[i]]
```

Using Do:

```Do[Print[i], {i, 10, 0, -1}]
```

Using Scan:

```Scan[Print, Range[10, 0, -1]]
```

```    for k = 10:-1:0,
printf('%d\n',k)
end;
```

A vectorized version of the code is

```  printf('%d\n',10:-1:0);
```

## Maxima

```for i from 10 thru 0 step -1 do print(i);
```

## MAXScript

```for i in 10 to 0 by -1 do print i
```

## Mercury

:- module loops_downward_for. :- interface.

:- import_module io. :- pred main(io::di, io::uo) is det.

:- implementation. :- import_module int.

main(!IO) :- Print = (pred(I::in, !.IO::di, !:IO::uo) is det :- io.write_int(I, !IO), io.nl(!IO) ), int.fold_down(Print, 1, 10, !IO).

```

## Metafont

```metafont
for i = 10 step -1 until 0: show i; endfor
end
```

The basic set of macros for Metafont defines downto, so that we can write

```

## Microsoft Small Basic

```microsoftsmallbasic

For i = 10 To 0 Step -1
TextWindow.WriteLine(i)
EndFor

```

=={{header|МК-61/52}}== 1 0 П0 ИП0 L0 03 С/П

```

```modula2
MODULE Downward;
IMPORT InOut;

VAR
i: INTEGER;

BEGIN
FOR i := 10 TO 0 BY -1 DO
InOut.WriteInt(i, 2);
InOut.WriteLn
END
END Downward.
```

```FOR i := 10 TO 0 BY -1 DO
IO.PutInt(i);
END;
```

## MUMPS

```LOOPDOWN
NEW I FOR I=10:-1:1 WRITE I WRITE:I'=1 ", "
KILL I QUIT
```

## NewLISP

```(for (i 10 0)
(println i))
```

## Nim

```for x in countdown(10,0): echo(x)
```

{{out}}

```10
9
8
7
6
5
4
3
2
1
0
```

## Nemerle

```for (i = 10; i >= 0; i--) {WriteLine(\$"\$i")}
```
```foreach (i in [10, 9 .. 0]) {WriteLine(\$"\$i")}
```

## NetRexx

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

say
say 'Loops/Downward for'

loop i_ = 10 to 0 by -1
say i_.right(2)
end i_

```

=={{header|NS-HUBASIC}}== 10 FOR 1=10 TO 0 STEP -1 20 PRINT I 30 NEXT

```

```oberon2
FOR i := 10 TO 0 BY -1 DO
Out.Int(i,0);
END;
```

## Objeck

```
for(i := 10; i >= 0; i--;) {
i->PrintLine();
};

```

## OCaml

```for i = 10 downto 0 do
Printf.printf "%d\n" i
done
```

## Octave

```for i = 10:-1:0
% ...
endfor
```

## Oforth

```10 0 -1 step: i [ i println ]
```

## Oz

```for I in 10..0;~1 do
{Show I}
end
```

## PARI/GP

```forstep(n=10,0,-1,print(n))
```

## Pascal

```for i := 10 downto 0 do
writeln(i);
```

## Peloton

English fixed-length opcodes

```0|<@ SAYVALFOR>...</@>|10|-1</@>
```

Simplified Chinese variable-length opcodes

```<# 迭代迭代次数字串字串字串字串>0|<# 显示值迭代次数>...</#>|10|-1</#>
```

## Perl

```foreach (reverse 0..10) {
print "\$_\n";
}
```

## Perl 6

{{works with|Rakudo Star|2010.08}}

```for 10 ... 0 {
.say;
}
```

## Phix

```for i=10 to 0 by -1 do
?i
end for
```

## PHP

```for (\$i = 10; \$i >= 0; \$i--)
echo "\$i\n";
```

or

```foreach (range(10, 0) as \$i)
echo "\$i\n";
```

## PicoLisp

```(for (I 10 (ge0 I) (dec I))
(println I) )
```

or:

```(mapc println (range 10 0))
```

## Pike

```int main(){
for(int i = 10; i >= 0; i--){
write(i + "\n");
}
}
```

## PL/I

```
do i = 10 to 0 by -1;
put skip list (i);
end;

```

## Pop11

```lvars i;
for i from 10 by -1 to 0 do
printf(i, '%p\n');
endfor;
```

## PowerShell

```for (\$i = 10; \$i -ge 0; \$i--) {
\$i
}
```

Alternatively, the range operator might be used as well which simply returns a contiguous range of integers:

```

## PureBasic

```PureBasic
For i=10 To 0 Step -1
Debug i
Next
```

## Prolog

Although Prolog has a between(Lo,Hi,Value) iterator, there is no built in equivalent for iterating descending values. This is not a show stopper, as it's easy enough to write one.

```rfor(Hi,Lo,Hi) :- Hi >= Lo.
rfor(Hi,Lo,Val) :- Hi > Lo, H is Hi - 1, !, rfor(H,Lo,Val).

reverse_iter :-
rfor(10,0,Val), write(Val), nl, fail.
reverse_iter.
```
```?- reverse_iter.
10
9
8
7
6
5
4
3
2
1
0
true.

```

## Python

```for i in xrange(10, -1, -1):
print i
```

### List comprehension

```[i for i in xrange(10, -1, -1)]
```
```import pprint
pprint.pprint([i for i in xrange(10, -1, -1)])

```

## R

```for(i in 10:0) {print(i)}
```

## Racket

```
#lang racket

(for ([i (in-range 10 -1 -1)])
(displayln i))

```

## REBOL

```for i 10 0 -1 [print i]
```

## Retro

```11 [ putn space ] iterd
```

## REXX

### version 1

(equivalent to version 2 and version 3)

```  do j=10  to 0  by -1
say j
end
```

### version 2

(equivalent to version 1 and version 3)

```  do j=10  by -1  to 0
say j
end
```

### version 3

(equivalent to version 1 and version 2)

Anybody who programs like this should be hunted down and shot like dogs!

Hurrumph! Hurrumph!

```  do j=10  by -2  to 0
say j
j=j+1     /*this increments the  DO  index.   Do NOT program like this! */
end
```

### version 4

This example isn't compliant to the task, but it shows that the increment/decrement can be a non-integer:

```  do j=30  to 1  by -.25
say j
end
```

## Ring

count from 10 to 0 by -1 step:

```
for i = 10 to 0 step -1 see i + nl next

```

## Ruby

```10.downto(0) do |i|
puts i
end
```

## Rust

```fn main() {
for i in (0..=10).rev() {
println!("{}", i);
}
}
```

## Salmon

```for (x; 10; x >= 0; -1)
x!;
```

## Sather

```class MAIN is
main is
i:INT;
loop i := 10.downto!(0);
#OUT  + i + "\n";
end;
end;
end;
```

## Scala

```for(i <- 10 to 0 by -1) println(i)
//or
10 to 0 by -1 foreach println
```

## Scheme

```(do ((i 10 (- i 1)))
((< i 0))
(display i)
(newline))
```

## Seed7

```for i range 10 downto 0 do
writeln(i);
end for;
```

## Scilab

{{works with|Scilab|5.5.1}} for i=10:-1:0 printf("%d\n",i) end

```
{{out}}
<pre style="height:20ex">
10
9
8
7
6
5
4
3
2
1
0

```

## Sidef

'''for(;;)''' loop:

```for (var i = 10; i >= 0; i--) {
say i
}
```

'''for-in''' loop:

```for i in (11 ^.. 0) {
say i
}
```

'''.each''' method:

```10.downto(0).each { |i|
say i
}
```

## Simula

```BEGIN
Integer i;
for i := 10 step -1 until 0 do
BEGIN
OutInt(i, 2);
OutImage
END
END
```

## Slate

```10 downTo: 1 do: [| :n | print: n]
```

## Smalltalk

```10 to: 1 by: -1 do:[:aNumber |
aNumber display.
Character space display.
]
```

## SNOBOL4

```        COUNT = 10
LOOP    OUTPUT = COUNT
COUNT = COUNT - 1
GE(COUNT, 0)     :S(LOOP)
END
```

## SNUSP

```++++++++++!/- @!\=@\.@@@-@-----#   atoi
\n      counter  #\?>.</  \ @@@+@+++++#   itoa
loop
```

## Sparkling

```= 0; i-- {
print(i);
}
```

## Spin

{{works with|BST/BSTC}} {{works with|FastSpin/FlexSpin}} {{works with|HomeSpun}} {{works with|OpenSpin}}

```con
_clkmode = xtal1 + pll16x
_clkfreq = 80_000_000

obj
ser : "FullDuplexSerial.spin"

pub main | n
ser.start(31, 30, 0, 115200)

repeat n from 10 to 0
ser.dec(n)
ser.tx(32)

waitcnt(_clkfreq + cnt)
ser.stop
cogstop(0)
```

{{out}}

```10 9 8 7 6 5 4 3 2 1 0
```

## SPL

``` i, 10..0,-1
#.output(i)
<
```

## SSEM

The SSEM can't print, so the results are stored in an array at addresses 22 to 31. Array access is done using self-modifying code: on each iteration we subtract the current value of n (stored at address 18) from the illegal instruction c to 32, yielding the actual instruction we use to store n into the array.

```10001000000000100000000000000000   0. -17 to c
11001000000001100000000000000000   1. c to 19
11001000000000100000000000000000   2. -19 to c
01001000000000010000000000000000   3. Sub. 18
00010000000001100000000000000000   4. c to 8
01001000000000100000000000000000   5. -18 to c
11001000000001100000000000000000   6. c to 19
11001000000000100000000000000000   7. -19 to c
00000000000000000000000000000000   8. generated at run time
11110000000000010000000000000000   9. Sub. 15
01001000000001100000000000000000  10. c to 18
11110000000000010000000000000000  11. Sub. 15
00000000000000110000000000000000  12. Test
00001000000000000000000000000000  13. 16 to CI
00000000000001110000000000000000  14. Stop
10000000000000000000000000000000  15. 1
11111111111111111111111111111111  16. -1
00000100000001100000000000000000  17. c to 32
01010000000000000000000000000000  18. 10
```

## Stata

See '''[https://www.stata.com/help.cgi?forvalues forvalues]''' and '''[https://www.stata.com/help.cgi?foreach foreach]''' in Stata help.

```forvalues n=10(-1)0 {
display `n'
}

forvalues n=10 9 to 0 {
display `n'
}

foreach n of numlist 10/0 {
display `n'
}
```

## Swift

```for i in stride(from: 10, through: 0, by: -1) {
println(i)
}
```

Alternately:

```for i in lazy(0...10).reverse() {
println(i)
}
```

In Swift 1.2 Alternately:

```for i in reverse(0 ... 10) {
println(i)
}
```

Alternately (removed in Swift 3):

```= 0; i-- {
println(i)
}
```

Swift 3:

```for i in (0...10).reversed() {
print(i)
}
```

## Tcl

```for {set i 10} {\$i >= 0} {incr i -1} {
puts \$i
}
# puts "We have liftoff!"
```

```
:For(I,10,0,-1
:Disp I
:End

```

```Local i
For i, 10, 0, –1
Disp i
EndFor
```

## Trith

```10 inc iota reverse [print] each
```
```10 [dup print dec] [dup 0 >=] while drop
```

```
\$\$ MODE TUSCRIPT
LOOP n=10,0,-1
PRINT n
ENDLOOP

```

## UnixPipes

{{works with|OpenBSD|4.9}}

```yes '' | cat -n | head -n 11 | while read n; do
expr \$n - 1
done | tail -r
```

This pipe uses several nonstandard commands: `cat -n` and `tail -r` might not work with some systems. If there is no `tail -r`, try `tac`.

## UNIX Shell

{{works with|Bourne Shell}}

```i=10
while test \$i -ge 0; do
echo \$i
i=`expr \$i - 1`
done

# or

jot - 10 0 -1

# or

seq 10 -1 0
```

{{works with|bash}}

```for(( Z=10; Z>=0; Z-- )); do
echo \$Z
done

#or

for Z in {10..0}; do
echo \$Z
done

```

## Ursa

```decl int i
for (set i 10) (> i -1) (dec i)
out i endl console
end for
```

## V

```10
[0 >]
[dup puts pred]
while
```

## VBA

```For i = 10 To 0 Step -1
Debug.Print i
Next i
```

## Vedit macro language

```for (#1 = 10; #1 >= 0; #1--) {
Num_Type(#1)
}
```

## Visual Basic .NET

```For i = 10 To 0 Step -1
Console.WriteLine(i)
Next
```

## Wart

for i 10 (i >= 0) --i prn i

```

## XPL0

```XPL0
include c:\cxpl\codes;          \intrinsic 'code' declarations
int I;
for I:= 10 downto 0 do
[IntOut(0, I); CrLf(0)]
```

## zkl

```foreach n in ([10..0,-1]){ println(n) }
[10..0,-1].apply() //-->L(10,9,8,7,6,5,4,3,2,1,0)
// tail recursion
fcn(n){ n.println(); if(n==0)return(); return(self.fcn(n-1)) }(10)
```

## ZX Spectrum Basic

```10 FOR l = 10 TO 0 STEP -1
20 PRINT l
30 NEXT l
```