Loops/N plus one half

Loops/N plus one half
You are encouraged to solve this task according to the task description, using any language you may know.

Quite often one needs loops which, in the last iteration, execute only part of the loop body. The goal of this task is to demonstrate the best way to do this.

Write a loop which writes the comma-separated list

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

using separate output statements for the number and the comma from within the body of the loop.

See also: Loop/Break

ACL2

ACL2 does not have loops, but this is close:

(defun print-list (xs)
   (progn$ (cw "~x0" (first xs))
           (if (endp (rest xs))
               (cw (coerce '(#\Newline) 'string))
               (progn$ (cw ", ")
                       (print-list (rest xs))))))

Ada

with Ada.Text_Io; use Ada.Text_Io;
with Ada.Integer_Text_Io; use Ada.Integer_Text_Io;
 
procedure Loop_And_Half is
   I : Positive := 1;
begin
   loop
      Put(Item => I, Width => 1);
      exit when I = 10;
      Put(", ");
      I := I + 1;
   end loop;
   New_Line;
end Loop_And_Half;

ALGOL 68

Works with: ALGOL 68 version Standard - no extensions to language used

Works with: ALGOL 68G version Any - tested with release mk15-0.8b.fc9.i386

Works with: ELLA ALGOL 68 version Any (with appropriate job cards) - tested with release 1.8.8d.fc9.i386

There are three common ways of achieving n+½ loops:

FOR i WHILE print(whole(i, -2)); # WHILE # i < 10 DO print(", ")   OD;   print(new line)

FOR i TO 10 DO print(whole(i, -2)); IF i < 10 THEN print(", ") FI OD;   print(new line)

FOR i DO print(whole(i, -2)); IF i >= 10 THEN GO TO done FI; print(", ")   OD; done: print(new line)

Output for all cases above:

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

AmigaE

PROC main()
  DEF i
  FOR i := 1 TO 10
    WriteF('\d', i)
    EXIT i = 10
    WriteF(', ')
  ENDFOR
ENDPROC

AutoHotkey

Loop, 9                ; loop 9 times
{
  output .= A_Index    ; append the index of the current loop to the output var
  If (A_Index <> 9)    ; if it isn't the 9th iteration of the loop
    output .= ", "     ; append ", " to the output var
}
MsgBox, %output%

AutoIT

 
#cs ----------------------------------------------------------------------------
 
 AutoIt Version: 3.3.8.1
 Author:         Alexander Alvonellos
 
 Script Function:
	Output a comma separated list from 1 to 10, and on the tenth iteration of the
	output loop, only perform half of the loop.
 
#ce ----------------------------------------------------------------------------
 
Func doLoopIterative()
		Dim $list = ""
		For $i = 1 To 10 Step 1
			$list = $list & $i
			If($i = 10) Then ExitLoop
			$list = $list & ", "
		Next
		return $list & @CRLF
EndFunc
 
Func main()
	ConsoleWrite(doLoopIterative())
EndFunc
 
main()
 

AWK

$ awk 'BEGIN{for(i=1;i<=10;i++){printf i;if(i<10)printf ", "};print}'
1, 2, 3, 4, 5, 6, 7, 8, 9, 10

BASIC

Works with: FreeBASIC version 0.20

Works with: RapidQ

DIM i AS INTEGER
 
FOR i=1 TO 10
    PRINT i;
    IF i=10 THEN EXIT FOR
    PRINT ", ";
NEXT i

ZX Spectrum Basic

To terminate a loop on the ZX Spectrum, set the loop counter to a value that will exit the loop, before jumping to the NEXT statement.

 
10 FOR i=1 TO 10
20 PRINT i;
30 IF i=10 THEN GOTO 50
40 PRINT ", ";
50 NEXT i
 

BBC BASIC

      FOR i% = 1 TO 10
        PRINT ; i% ;
        IF i% <> 10 PRINT ", ";
      NEXT
      PRINT

Befunge

1+>::.9`#@_" ,",,

This code is a good answer. However, most Befunge implementations print a " " after using . (output number), so this program prints "1 , 2 , 3 ..." with unnecessary extra spaces. A bypass for this is possible, yet slightly less sane:

"0"                v
1+>::"9"`#v_," ,",,>
          >"01",,@

C

Translation of: C++

#include <stdio.h>
 
int main()
{
  int i;
  for (i = 1; i <= 10; i++) {
    printf("%d", i);
    printf(i == 10 ? "\n" : ", ");
  }
  return 0;
}

C++

#include <iostream>
 
int main()
{
  for (int i = 1; ; i++)
  {
    std::cout << i;
    if (i == 10)
      break;
    std::cout << ", ";
  }
  std::cout << std::endl;
  return 0;
}

C#

using System;
 
class Program
{
    static void Main(string[] args)
    {
        for (int i = 1; ; i++)
        {
            Console.Write(i);
            if (i == 10) break;
            Console.Write(", ");
        }
        Console.WriteLine();
    }
}

Clojure

 
; Functional version
(apply str (interpose ", " (range 1 11)))
 
; Imperative version
(loop [n 1]
   (printf "%d" n)
   (if (< n 10)
       (do
	(print ", ")
	(recur (inc n)))))
 

ColdFusion

With tags:

<cfloop index = "i" from = "1" to = "10">
  #i#
  <cfif i EQ 10>
    <cfbreak />
  </cfif>
  , 
</cfloop>

With script:

<cfscript>
  for( i = 1; i <= 10; i++ ) //note: the ++ notation works only on version 8 up, otherwise use i=i+1
  {
    writeOutput( i );
 
    if( i == 10 )
    {
      break;
    }
    writeOutput( ", " );
  }
</cfscript>

CoffeeScript

 
# Loop plus half.  This code shows how to break out of a loop early
# on the last iteration.  For the contrived example, there are better
# ways to generate a comma-separated list, of course.
start = 1
end = 10
s = ''
for i in [start..end]
  # the top half of the loop executes every time
  s += i
  break if i == end
  # the bottom half of the loop is skipped for the last value
  s += ', '
console.log s
 

Common Lisp

 
(loop for i from 1 below 10 do 
        (princ i) (princ ", ")
        finally (princ i))
 

or

(loop for i from 1 upto 10 do
  (princ i)
  (if (= i 10) (return))
  (princ ", "))

but for such simple tasks we can use format's powers:

 
(format t "~{~a~^, ~}" (loop for i from 1 to 10 collect i))
 

D

Iterative

import std.stdio;
 
void main() {
    for (int i = 1; ; i++) {
        write(i);
        if (i >= 10)
            break;
        write(", ");
    }
 
    writeln();
}

Output:

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

Functional Style

Same output.

import std.stdio, std.range, std.algorithm, std.conv, std.string;
 
void main() {
    iota(1, 11).map!text().join(", ").writeln();
}

Delphi

program LoopsNPlusOneHalf;
 
{$APPTYPE CONSOLE}
 
var
  i: integer;
const
  MAXVAL = 10;
begin
  for i := 1 to MAXVAL do
  begin
    Write(i);
    if i < MAXVAL then
      Write(', ');
  end;
  Writeln;
end.

DWScript

var i : Integer;
 
for i := 1 to 10 do begin
   Print(i);
   if i < 10 then
      Print(', ');
end;

E

A typical loop+break solution:

var i := 1
while (true) {
    print(i)
    if (i >= 10) { break }
    print(", ")
    i += 1
}

Using the loop primitive in a semi-functional style:

var i := 1
__loop(fn {
    print(i)
    if (i >= 10) {
        false
    } else {
        print(", ")
        i += 1
        true 
    }
})

Erlang

%% Implemented by Arjun Sunel
-module(loop).
-export([main/0]).
 
main() ->
	for_loop(1).    
 
 for_loop(N) ->
 	if N < 10 ->
		io:format("~p, ",[N] ),
		for_loop(N+1);
	true ->
		io:format("~p\n",[N])
	end.	
 

Euphoria

 
for i = 1 to 10 do
    printf(1, "%g", {i})
    if i < 10 then
        puts(1, ", ")
    end if
end for
 

While, yes, use of exit would also work here, it is slightly faster to code it this way, if only the last iteration has something different.

F#

Functional version that works for lists of any length

 
let rec print (lst : int list) =
    match lst with
    | hd :: [] ->
        printf "%i " hd
    | hd :: tl ->
        printf "%i, " hd
        print tl
    | [] -> printf "\n"
 
print [1..10] 
 

Factor

: print-comma-list ( n -- )
    [ [1,b] ] keep '[
        [ number>string write ]
        [ _ = [ ", " write ] unless ] bi
    ] each nl ;

FALSE

1[$9>~][$.", "1+]#.

Fantom

 
class Main
{
  public static Void main ()
  {
    for (Int i := 1; i <= 10; i++)
    {
      Env.cur.out.writeObj (i)
      if (i == 10) break
      Env.cur.out.writeChars (", ")
    }
    Env.cur.out.printLine ("")
  }
}
 

Forth

: comma-list ( n -- )
  dup 1 ?do  i 1 .r ." , " loop
  . ;

: comma-list ( n -- )
  dup 1+ 1 do
    i 1 .r
    dup i = if leave then   \ or DROP UNLOOP EXIT to exit loop and the function
    [char] , emit space
  loop drop ;

: comma-list ( n -- )
  1
  begin  dup 1 .r
         2dup <>
  while  ." , " 1+
  repeat 2drop ;

Fortran

Works with: Fortran version 77 and later

C     WARNING: This program is not valid ANSI FORTRAN 77 code. It uses
C     two nonstandard characters on the lines labelled 5001 and 5002.
C     Many F77 compilers should be okay with it, but it is *not*
C     standard.
      PROGRAM LOOPPLUSONEHALF
        INTEGER I, TEN
C       I'm setting a parameter to distinguish from the label 10.
        PARAMETER (TEN = 10)
 
        DO 10 I = 1, TEN
C         Write the number only.
          WRITE (*,5001) I
 
C         If we are on the last one, stop here. This will make this test
C         every iteration, which can slow your program down a little. If
C         you want to speed this up at the cost of your own convenience,
C         you could loop only to nine, and handle ten on its own after
C         the loop is finished. If you don't care, power to you.
          IF (I .EQ. TEN) GOTO 10
 
C         Append a comma to the number.
          WRITE (*,5002) ','
   10   CONTINUE
 
C       Always finish with a newline. This programmer hates it when a
C       program does not end its output with a newline.
        WRITE (*,5000) ''
        STOP
 
 5000   FORMAT (A)
 
C       Standard FORTRAN 77 is completely incapable of completing a
C       WRITE statement without printing a newline. This program would
C       be much more difficult (i.e. impossible) to write in the ANSI
C       standard, without cheating and saying something like:
C
C           WRITE (*,*) '1, 2, 3, 4, 5, 6, 7, 8, 9, 10'
C
C       The dollar sign at the end of the format is a nonstandard
C       character. It tells the compiler not to print a newline. If you
C       are actually using FORTRAN 77, you should figure out what your
C       particular compiler accepts. If you are actually using Fortran
C       90 or later, you should replace this line with the commented
C       line that follows it.
 5001   FORMAT (I3, $)
 5002   FORMAT (A, $)
C5001   FORMAT (T3, ADVANCE='NO')
C5001   FORMAT (A, ADVANCE='NO')
      END

Works with: Fortran version 90 and later

i = 1
do
  write(*, '(I0)', advance='no') i
  if ( i == 10 ) exit
  write(*, '(A)', advance='no') ', '
  i = i + 1
end do
write(*,*)

GML

str = ""
for(i = 1; i <= 10; i += 1)
    {
    str += string(i)
    if(i != 10)
        str += ", "
    }
show_message(str)

Go

package main
 
import "fmt"
 
func main() {
    for i := 1; ; i++ {
        fmt.Print(i)
        if i == 10 {
            fmt.Println("")
            break
        }
        fmt.Print(", ")
    }
}

Groovy

Solution:

for(i in (1..10)) {
    print i
    if (i == 10) break
    print ', '
}

Output:

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

Haskell

loop :: IO ()
loop = mapM_ action [1 .. 10]
  where action n = do
            putStr $ show n
            putStr $ if n == 10 then "\n" else ", "

It is, however, arguable whether mapM_ counts as a loop.

HicEst

DO i = 1, 10
    WRITE(APPend) i
    IF(i < 10) WRITE(APPend) ", "
ENDDO

IDL

Nobody would ever use a loop in IDL to output a vector of numbers - the requisite output would be generated something like this:

print,indgen(10)+1,format='(10(i,:,","))'

However if a loop had to be used it could be done like this:

for i=1,10 do begin
 print,i,format='($,i)'
 if i lt 10 then print,",",format='($,a)'
endfor

(which merely suppresses the printing of the comma in the last iteration);

or like this:

for i=1,10 do begin
 print,i,format='($,i)'
 if i eq 10 then break
 print,",",format='($,a)'
end

(which terminates the loop early if the last element is reached).

Icon and Unicon

procedure main()
every writes(i := 1 to 10) do 
   if i = 10 then break write()
   else writes(", ")
end

The above can be written more succinctly as:

every writes(c := "",1 to 10) do c := ","
 

J

output=: verb define
  buffer=: buffer,y
)
 
loopy=: verb define
  buffer=: ''
  for_n. 1+i.10 do.
    output ":n
    if. n<10 do.
      output ', '
    end.
  end.
  smoutput buffer
)

Example use:

   loopy 0
1, 2, 3, 4, 5, 6, 7, 8, 9, 10

That said, note that neither loops nor output statements are necessary:

   ;}.,(', ' ; ":)&> 1+i.10
1, 2, 3, 4, 5, 6, 7, 8, 9, 10

And, note also that this sort of data driven approach can also deal with more complex issues:

   commaAnd=: ":&.> ;@,. -@# {. (<;._1 '/ and /') ,~ (<', ') #~ #  
   commaAnd i.5
0, 1, 2, 3 and 4

Java

public static void main(String[] args) {
    for (int i = 1; ; i++) {
        System.out.print(i);
        if (i == 10)
            break;
        System.out.print(", ");
    }
    System.out.println();
}

JavaScript

function loop_plus_half(start, end) {
    var str = '',
        i;
    for (i = start; i <= end; i += 1) {
        str += i;
        if (i === end) {
          break;
        }
        str += ', ';
    }
    return str;
}
 
alert(loop_plus_half(1, 10));

K

   p:{`0:$x} / output
   i:1;do[10;p[i];p[:[i<10;", "]];i+:1];p@"\n"
1, 2, 3, 4, 5, 6, 7, 8, 9, 10

Alternative solutions:

   10 {p@x;p@:[x<10;", ";"\n"];x+1}\1;
   {p@x;p@:[x<10;", ";"\n"];x+1}'1+!10; /variant

LabVIEW

This image is a VI Snippet, an executable image of LabVIEW code. The LabVIEW version is shown on the top-right hand corner. You can download it, then drag-and-drop it onto the LabVIEW block diagram from a file browser, and it will appear as runnable, editable code.

Lang5

: ,  dup ", " 2 compress "" join ;
1 do dup 10 != if dup , . 1 + else . break then loop

Word: Loops/For#Lang5

: 2string  2 compress "" join ;
: ,  dup 10 != if ", " 2string then ;
1 10 "dup , . 1+" times

Liberty BASIC

Keyword 'exit' allows the termination.

 
for i =1 to 10
    print i;
    if i =10 then exit for
    print ", ";
next i
end
 

Lisaac

Section Header
 
+ name := LOOP_AND_HALF;
 
Section Public
 
- main <- (
  + i : INTEGER;
 
  i := 1;
  {
    i.print;
    i = 10
  }.until_do {
    ", ".print;
    i := i + 1;
  };
  '\n'.print;
);

Logo

to comma.list :n
  repeat :n-1 [type repcount type "|, |]
  print :n
end
 
comma.list 10

Lua

Translation of C:

for i = 1, 10 do
  io.write(i)
  if i == 10 then break end
  io.write", "
end

M4

define(`break',
   `define(`ulim',llim)')
define(`for',
   `ifelse($#,0,``$0'',
   `define(`ulim',$3)`'define(`llim',$2)`'ifelse(ifelse($3,`',1,
         `eval($2<=$3)'),1,
   `pushdef(`$1',$2)$4`'popdef(`$1')$0(`$1',incr($2),ulim,`$4')')')')
 
for(`x',`1',`',
   `x`'ifelse(x,10,`break',`, ')')

Mathematica

i = 1; s = "";
While[True,
 s = s <> ToString@i;
 If[i == 10, Break[]];
 s = s <> ",";
 i++;
 ]
s

MATLAB / Octave

Vectorized form:

 	printf('%i, ',1:9); printf('%i\n',10);

Explicite loop:

   for k=1:10,
      printf('%i', k); 
   if k==10, break; end;
      printf(', ');
   end; 
   printf('\n');

Output:

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

MAXScript

for i in 1 to 10 do
(
    format "%" i
    if i == 10 then exit
    format "%" ", "
)

Make

NEXT=`expr $* + 1`
MAX=10
RES=1
 
all: 1-n;
 
$(MAX)-n:
       @echo $(RES)
 
%-n:
       @-make -f loop.mk $(NEXT)-n MAX=$(MAX) RES=$(RES),$(NEXT)

Invoking it

|make -f loop.mk MAX=10
1,2,3,4,5,6,7,8,9,10

Metafont

Since message append always a newline, we need building the output inside a string, and then we output it.

last := 10;
string s; s := "";
for i = 1 upto last:
  s := s & decimal i;
  if i <> last: s := s & ", " fi;
endfor
message s;
end

Modula-3

MODULE Loop EXPORTS Main;
 
IMPORT IO, Fmt;
 
VAR i := 1;
 
BEGIN
  LOOP
    IO.Put(Fmt.Int(i));
    IF i = 10 THEN EXIT; END;
    IO.Put(", ");
    i := i + 1;
  END;
  IO.Put("\n");
END Loop.

Nemerle

foreach (i in [1 .. 10])
{
    Write(i);
    unless (i == 10) Write(", ");
}

MUMPS

LOOPHALF
 NEW I
 FOR I=1:1:10 DO
 .WRITE I
 .IF I'=10 WRITE ", "
 QUIT
 ;Alternate
 NEW I FOR I=1:1:10 WRITE I WRITE:I'=10 ", "
 KILL I QUIT

Output:

USER>D LOOPHALF^ROSETTA
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
USER>D LOOPHALF+7^ROSETTA
1, 2, 3, 4, 5, 6, 7, 8, 9, 10

NetRexx

/* NetRexx */
options replace format comments java crossref savelog symbols nobinary
 
  say
  say 'Loops/N plus one half'
 
  rs = ''
  istart = 1
  iend   = 10
  loop i_ = istart to iend
    rs = rs || i_.right(3)
    if i_ < iend then do
      rs = rs','
      end
    end i_
  say rs
 

Objeck

 
bundle Default {
  class Hello {
    function : Main(args : String[]) ~ Nil {
      for(i := 1; true; i += 1;) {
        i->Print();
        if(i = 10) {
          break;
        };
        ", "->Print();
      };
      '\n'->Print();
    }
  }
}
 

OCaml

let last = 10 in
for i = 1 to last do
  print_int i;
  if i <> last then
    print_string ", ";
done;
print_newline();

let ints = [1; 2; 3; 4; 5; 6; 7; 8; 9; 10] in
let str_ints = List.map string_of_int ints in
print_endline (String.concat ", " str_ints);

Oz

Using a for-loop:

 
for N in {List.number 1 10 1} break:Break do
   {System.printInfo N}
   if N == 10 then {Break} end
   {System.printInfo ", "}
end

However, it seems more natural to use a left fold:

declare
  fun {CommaSep Xs}
     case Xs of nil then nil
     [] X|Xr then
	{FoldL Xr 
	 fun {$ Z X} Z#", "#X end
	 X}
     end
  end
in
  {System.showInfo {CommaSep {List.number 1 10 1}}}

PARI/GP

n=0;
while(1,
  print1(n++);
  if(n>9, break);
  print1(", ")
);

Pascal

program numlist(output);
 
var
  i: integer;
 
begin
  for i := 1 to 10 do
    begin
      write(i);
      if i <> 10 then
        write(', ')
    end;
  writeln;
end.

Perl

foreach my $i (1..10) {
    print $i;
    last if $i == 10;
    print ', ';
}
print "\n";

Perl 6

for 1 .. 10 {
    .print;
    last when 10;
    print ', ';
}
 
print "\n";

PHP

for ($i = 1; $i <= 11; $i++) {
    echo $i;
    if ($i == 10)
        break;
    echo ', ';
}
echo "\n";

PicoLisp

(for N 10
   (prin N)
   (T (= N 10))
   (prin ", ") )

Pike

 
int main(){
   for(int i = 1; i <= 11; i++){
      write(sprintf("%d",i));
      if(i == 10){
         break;
      }
      write(", ");
   }
   write("\n");
}

PL/I

 
do i = 1 to 10;
   put edit (trim(i)) (a);
   if i < 10 then put edit (', ') (a);
end;
 

Pop11

lvars i;
for i from 1 to 10 do
    printf(i, '%p');
    quitif(i = 10);
    printf(', ', '%p');
endfor;
printf('\n', '%p');

PowerShell

Translation of: C

for ($i = 1; $i -le 10; $i++) {
    Write-Host -NoNewLine $i
    if ($i -eq 10) {
        Write-Host
        break
    }
    Write-Host -NoNewLine ", "
}

An interesting alternative solution, although not strictly a loop, even though switch certainly loops over the given range.

switch (1..10) {
    { $true }     { Write-Host -NoNewLine $_ }
    { $_ -lt 10 } { Write-Host -NoNewLine ", " }
    { $_ -eq 10 } { Write-Host }
}

PureBasic

x=1
Repeat 
  Print(Str(x))
  x+1
  If x>10: Break: EndIf
  Print(", ")
ForEver

Python

The particular pattern and example chosen in the task description is recognised by the Python language and there are more idiomatic ways to achieve the result that don't even require an explicit conditional test such as:

print ( ', '.join(str(i+1) for i in range(10)) )

But the named pattern is shown by code such as the following:

>>> from sys import stdout
>>> write = stdout.write
>>> n, i = 10, 1
>>> while True:
    write(i)
    i += 1
    if i > n:
        break
    write(', ')
 
 
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
>>>

R

The natural way to solve this task in R is:

paste(1:10, collapse=", ")

The task specifies that we should use a loop however, so this more verbose code is needed.

for(i in 1:10)
{
   cat(i)
   if(i==10) 
   {
      cat("\n")
      break
   }
   cat(", ")
}

Racket

#lang racket
(for ((i (in-range 1 15)))
  (display i)
  #:break (= 10 i)
  (display ", "))

Gives the desired output.

REBOL

rebol [
    Title: "Loop Plus Half"
    Date: 2009-12-16
    Author: oofoe
    URL: http://rosettacode.org/wiki/Loop/n_plus_one_half
]
 
repeat i 10 [
	prin i
	if 10 = i [break]
	prin ", "
]
print ""

REXX

two CHAROUTs

/*REXX program to display:              1,2,3,4,5,6,7,8,9,10            */
 
      do j=1  to 10
      call charout ,j                   /*write the DO loop index (no LF)*/
      if j<10  then call charout ,","   /*append a comma for 1-digit nums*/
      end    /*j*/
                                        /*stick a fork in it, we're done.*/

output

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

one CHAROUT

/*REXX program to display:              1,2,3,4,5,6,7,8,9,10            */
 
     do j=1  for 10                    /*using  FOR  is faster than  TO.*/
     call charout ,j || left(',',j<10) /*show  J,  maybe append a comma.*/
     end     /*j*/
                                       /*stick a fork in it, we're done.*/

output

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

Ruby

for i in 1..10 do
   print i
   break if i == 10
   print ", "
end
puts

Salmon

iterate (x; [1...10])
  {
    print(x);
    if (x == 10)
        break;;
    print(", ");
  };
print("\n");

Scheme

It is possible to use continuations:

(call-with-current-continuation
 (lambda (esc)
   (do ((i 1 (+ 1 i))) (#f)
     (display i)
     (if (= i 10) (esc (newline)))
     (display ", "))))

But usually making the tail recursion explicit is enough:

(let loop ((i 0))
  (display i)
  (if (= i 10)
      (newline)
      (begin
        (display ", ")
        (loop (+ 1 i)))))

Seed7

$ include "seed7_05.s7i";
 
const proc: main is func
  local
    var integer: number is 0;
  begin
    for number range 1 to 10 do
      write(number);
      if number < 10 then
        write(", ")
      end if;
    end for;
    writeln;
  end func;

SNOBOL4

It's idiomatic in Snobol to accumulate the result in a string buffer for line output, and to use the same statement for loop control and the comma.

loop    str = str lt(i,10) (i = i + 1) :f(out)
        str = str ne(i,10) ',' :s(loop)
out     output = str
end

Works with: Macro Spitbol

For the task description, it's possible (implementation dependent) to set an output variable to raw mode for character output within the loop. This example also breaks the loop explicitly.

        output('out',1,'-[-r1]')
loop    i = lt(i,10) i + 1 :f(end)
        out = i
        eq(i,10) :s(end)
        out = ',' :(loop)
end

Output:

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

SNUSP

@\>@\>@\>+++++++++<!/+.  >-?\#  digit and loop test
 |  |  \@@@+@+++++# \>>.<.<</    comma and space
 |  \@@+@@+++++#      
 \@@@@=++++#

Tcl

for {set i 1; set end 10} true {incr i} {
    puts -nonewline $i
    if {$i >= $end} break
    puts -nonewline ", "
}
puts ""

However, that's not how the specific task (printing 1..10 with comma separators) would normally be done. (Note, the solution below is not a solution to the half-looping problem.)

proc range {from to} {
    set result {}
    for {set i $from} {$i <= $to} {incr i} {
        lappend result $i
    }
    return $i
}
 
puts [join [range 1 10] ", "] ;# ==> 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

TI-89 BASIC

There is no horizontal cursor position on the program IO screen, so we concatenate strings instead.

Local str
"" → str
For i,1,10
  str & string(i) → str
  If i < 10 Then
    str & "," → str
  EndIf
EndFor
Disp str

TUSCRIPT

 
$$ MODE TUSCRIPT
line=""
LOOP n=1,10
 line=CONCAT (line,n)
 IF (n!=10) line=CONCAT (line,", ")
ENDLOOP
PRINT line
 

Output:

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

UnixPipes

The last iteration is handled automatically for us when there is no element in one of the pipes.

yes \ | cat -n | head -n 10 | paste -d\  - <(yes , | head -n 9) | xargs echo

UNIX Shell

for(( Z=1; Z<=10; Z++ )); do
    echo -e "$Z\c"
    if (( Z != 10 )); then
        echo -e ", \c"
    fi
done

Works with: Bash

for ((i=1;i<=$((last=10));i++)); do
  echo -n $i
  [ $i -eq $last ] && break
  echo -n ", "
done

V

[loop 
   [ [10 =] [puts]
     [true] [dup put ',' put succ loop]
   ] when].

Using it

|1 loop
=1,2,3,4,5,6,7,8,9,10

Vedit macro language

This example writes the output into current edit buffer.

for (#1 = 1; 1; #1++) {
    Num_Ins(#1, LEFT+NOCR)
    if (#1 == 10) { Break }
    Ins_Text(", ")
}
Ins_Newline

Visual Basic .NET

For i = 1 To 10
    Console.Write(i)
    If i = 10 Then Exit For
    Console.Write(", ")
Next

XPL0

codes CrLf=9, IntOut=11, Text=12;
int  N;
[for N:= 1 to 10 do     \best way to do this
        [IntOut(0, N);  if N#10 then Text(0, ", ")];
CrLf(0);
 
N:= 1;                  \way suggested by task statement
loop    [IntOut(0, N);
        if N=10 then quit;
        Text(0, ", ");
        N:= N+1;
        ];
CrLf(0);
]