Loops/For

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

“For” loops are used to make some block of code be iterated a number of times, setting a variable or parameter to a monotonically increasing integer value for each execution of the block of code. Common extensions of this allow other counting patterns or iterating over abstract structures other than the integers.

For this task, show how two loops may be nested within each other, with the number of iterations performed by the inner for loop being controlled by the outer for loop. Specifically print out the following pattern by using one for loop nested in another:

*
**
***
****
*****

ActionScript

var str:String = "";
for (var i:int = 1; i <= 5; i++) {
	for (var j:int = 1; j <= i; j++)
		str += "*";
	trace(str);
	str = "";
}

Ada

for I in 1..5 loop
   for J in 1..I loop
      Put("*");
   end loop;
   New_Line;
end loop;

ALGOL 68

Works with: ALGOL 68 version Revision 1 - no extensions to language used

Works with: ALGOL 68G version Any - tested with release 1.18.0-9h.tiny

Works with: ELLA ALGOL 68 version Any (with appropriate job cards) - tested with release 1.8-8d

FOR i TO 5 DO
   TO i DO
      print("*")
   OD;
  print(new line)
OD

Output:

*
**
***
****
*****

Alore

for i in 0 to 6
  for j in 0 to i
      Write('*')
  end
  WriteLn()
end
 

AmigaE

PROC main()
  DEF i, j
  FOR i := 1 TO 5
    FOR j := 1 TO i DO WriteF('*')
    WriteF('\n')
  ENDFOR
ENDPROC

AppleScript

set x to return
repeat with i from 1 to 5
	repeat with j from 1 to i
		set x to x & "*"
	end repeat
	set x to x & return
end repeat
return x

Output:

"
*
**
***
****
*****
" 

AutoHotkey

Gui, Add, Edit, vOutput r5 w100 -VScroll ; Create an Edit-Control
Gui, Show ; Show the window
Loop, 5 ; loop 5 times
{
  Loop, %A_Index% ; A_Index contains the Index of the current loop
  {
    output .= "*" ; append an "*" to the output var
    GuiControl, , Output, %Output% ; update the Edit-Control with the new content
    Sleep, 500 ; wait some(500ms) time, [just to show off]
  }
  Output .= (A_Index = 5) ? "" : "`n" ; append a new line to the output if A_Index is not "5"
}
Return ; End of auto-execution section

AWK

BEGIN {
  for(i=1; i < 6; i++) {
    for(j=1; j <= i; j++ ) {
      printf "*"
    }
    print
  }
}

Babel

star_triangle: { <- { { "*" << } iter times "\n" << } -> times }
main: { 10 star_triangle }
*
**
***
****
*****
******
*******
********
*********

The key operator here is 'iter' which gives the current iteration of the loop body it resides in, beginning with 0 and counting up.

BASIC

Works with: QuickBasic version 4.5

FOR i = 1 TO 5
   FOR j = 1 TO i
      PRINT "*";
   NEXT j
   PRINT
NEXT i

ZX Spectrum Basic

On the ZX Spectrum, we need line numbers:

 
10 FOR i = 1 TO 5
20 FOR j = 1 TO i
30 PRINT "*";
40 NEXT j
50 PRINT
60 NEXT i
 

Batch File

@ECHO OFF
SETLOCAL ENABLEDELAYEDEXPANSION
 
for /l %%i in (1,1,5) do (
    SET line=
    for /l %%j in (1,1,%%i) do (
        SET line=!line!*
    )
    ECHO !line!
)
 
ENDLOCAL

BBC BASIC

Works with: BBC BASIC for Windows

 
      FOR I% = 1 TO 5
        FOR J% = 1 TO I%
          PRINT"*";
        NEXT
        PRINT
      NEXT
 

bc

for (i = 1; i <= 5; i++) {
	for (j = 1; j <= i; j++) "*"
	"
"
}
quit

Befunge

1>:5`#@_:>"*",v
         | :-1<
 ^+1,+5+5<

Bracmat

  0:?i
&   whl
  ' ( !i+1:~>5:?i
    & 0:?k
    & whl'(!k+1:~>!i:?k&put$"*")
    & put$\n
    )
&
);

Brainf***

>>+++++++[>++++++[>+<-]<-]       place * in cell 3
+++++[>++[>>+<<-]<-]<<           place \n in cell 4
+++++[                           set outer loop count
[>+                              increment inner counter
>[-]>[-]<<[->+>+<<]>>[-<<+>>]<<  copy inner counter
>[>>.<<-]>>>.<<<                 print line
<<-]                             end inner loop
]                                end outer loop

Brat

1.to 5, { i |
  1.to i, { j |
    print "*"
  }
  print "\n"
}

C

int i, j;
for (i = 1; i <= 5; i++) {
  for (j = 1; j <= i; j++)
    putchar('*');
  puts("");
}

C++

for(int i = 1; i <= 5; ++i) {
  for(int j = 1; j <= i; j++)
    std::cout << "*";
  std::cout << std::endl;
}

C#

using System;
 
class Program {
    static void Main(string[] args)
    {
        for (int i = 0; i < 5; i++)
        {
            for (int j = 0; j <= i; j++)
            {
                Console.Write("*");
            }
            Console.WriteLine();
        }
    }
}

Chef

Asterisks Omelette.
 
This recipe prints a triangle of asterisks.
 
Ingredients.
5 eggs
1 onion
1 potato
42 ml water
10 ml olive oil
1 garlic
 
Method.
Put eggs into the mixing bowl.
Fold onion into the mixing bowl.
Put eggs into the mixing bowl.
Add garlic into the mixing bowl.
Fold eggs into the mixing bowl.
Chop onion.
Put onion into the mixing bowl.
Fold potato into the mixing bowl.
Put olive oil into the mixing bowl.
Mash potato.
Put water into the mixing bowl.
Mash potato until mashed.
Chop onion until choped.
Pour contents of the mixing bowl into the baking dish.
 
Serves 1.

COBOL

The DISPLAY function in OpenCOBOL always displays the value on the next available line, therefore the asterisks must be built up in a variable to be displayed when the asterisks have all been added.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. Display-Triangle.
 
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  Outer-Counter PIC 9.
       01  Inner-Counter PIC 9. 
 
       01  Output-Line   PIC X(10).
 
       PROCEDURE DIVISION.
       PERFORM VARYING Outer-Counter FROM 1 BY 1 UNTIL 5 < Outer-Counter
           MOVE SPACES TO Output-Line
 
           PERFORM VARYING Inner-Counter FROM 1 BY 1
                   UNTIL Outer-Counter < Inner-Counter
               MOVE "*" TO Output-Line (Inner-Counter:1)
           END-PERFORM
 
           DISPLAY Output-Line
       END-PERFORM
 
       GOBACK
       .
 

Clojure

(doseq [i (range 5), j (range (inc i))]
  (print "*")
  (if (= i j) (println)))

ColdFusion

Remove the leading space from the line break tag.

With tags:

<cfloop index = "i" from = "1" to = "5">
  <cfloop index = "j" from = "1" to = "#i#">
    *
  </cfloop>
  < br />
</cfloop>

With script:

<cfscript>
  for( i = 1; i <= 5; i++ )
  {
    for( j = 1; j <= i; j++ )
    {
      writeOutput( "*" );
    }
    writeOutput( "< br />" );
  }
</cfscript>

Common Lisp

(loop for i from 1 upto 5 do
  (loop for j from 1 upto i do
    (write-char #\*))
  (write-line ""))

(dotimes (i 5)
  (dotimes (j (+ i 1))
    (write-char #\*))
  (terpri))

(do ((i 1 (+ i 1)))
    ((> i 5))
  (do ((j 1 (+ j 1)))
      ((> j i))
    (write-char #\*))
  (terpri))

Creative Basic

 
OPENCONSOLE
 
FOR X=1 TO 5
 
	FOR Y=1 TO X
 
            PRINT"*",:'No line feed or carriage return after printing.
 
	NEXT Y
 
PRINT
 
NEXT X
 
PRINT:PRINT"Press any key to end."
 
DO:UNTIL INKEY$<>""
 
CLOSECONSOLE
 
END
 

D

import std.stdio: write, writeln;
 
void main() {
    for (int i; i < 5; i++) {
        for (int j; j <= i; j++)
            write("*");
        writeln();
    }
    writeln();
 
    foreach (i; 0 .. 5) {
        foreach (j; 0 .. i + 1)
            write("*");
        writeln();
    }
}

Output:

*
**
***
****
*****

*
**
***
****
*****

Dao

for( i = 1 : 5 ){
    for( j = 1 : i ) io.write( '*' )
    io.writeln()
}

Dart

main() {
    for (var i = 0; i < 5; i++)
        print(i);
}

dc

[...]sA defines the inner loop A and [...]sB defines the outer loop B. This program nests the entrance to loop A inside loop B.

Translation of: bc

[
 [*]P		[print asterisk]sz
 lj 1 + d sj	[increment j, leave it on stack]sz
 li !<A		[continue loop if i >= j]sz
]sA
[
 1 d sj		[j = 1, leave it on stack]sz
 li !<A		[enter loop A if i >= j]sz
 [
]P		[print newline]sz
 li 1 + d si	[increment i, leave it on stack]sz
 5 !<B		[continue loop if 5 >= i]sz
]sB
1 d si		[i = 1, leave it on stack]sz
5 !<B		[enter loop B if 5 >= i]sz

Delphi

program LoopFor;
 
{$APPTYPE CONSOLE}
 
var
  i, j: Integer;
begin
  for i := 1 to 5 do
  begin
    for j := 1 to i do
      Write('*');
    Writeln;
  end;
end.

DWScript

var i, j : Integer;
 
for i := 1 to 5 do begin
   for j := 1 to i do
      Print('*');
   PrintLn('');
end;

dodo0

fun for -> var, test, body, return    # define a for loop using recursion
(
   test(var) -> continue
   if (continue) ->
   (
      body(var) -> var
      for (var, test, body, return)
   )
   |
      return(var)
)
| for
 
fun upToFive (-> index, return) '<='(index, 5, return) | upToFive
 
for (1, upToFive) -> index, return
(
   fun countTheStars -> stars, return
   (
      'count'(stars) -> n
      '<'(n, index, return)   # continue until n = index
   )
   | countTheStars
 
   for ("*", countTheStars) -> prefix, return
      'str'(prefix, "*", return)
   | stars
 
   println(stars) ->
 
   'inc'(index, return)
)
| result
exit()

DMS

number i, j
for (i = 1; i <= 5; i++) 
{
    for (j = 1; j <= i; j++)
    {
        Result( "*" )
    }
    Result( "\n" )
}

E

for width in 1..5 {
    for _ in 1..width {
        print("*")
    }
    println()
}

This loop is a combination of for ... in ... which iterates over something and a..b which is a range object that is iteratable. (Also, writing a..!b excludes the value b.)

Ela

open console
 
loop m n | n < m = loop' n 0 $ writen "" $ loop m (n+1)
         | else = ()
         where loop' m n | n <= m = write "*" $ loop' m (n+1)
                         | else = ()

EGL

str string;
for ( i int to 5 )
   str = "";
   for ( j int to i )
      str += "*";
   end
   SysLib.writeStdout(str);
end

Erlang

%% Implemented by Arjun Sunel
-module(nested_loops).
-export([main/0, inner_loop/0]).
 
main() ->
	outer_loop(1).
 
inner_loop()->
	inner_loop(1).
 
inner_loop(N) when N rem 5 =:= 0 ->
	io:format("* ");
 
inner_loop(N) ->
	io:fwrite("* "),
	inner_loop(N+1).
 
outer_loop(N) when N rem 5 =:= 0 ->
	io:format("*");
 
outer_loop(N) ->
	outer_loop(N+1),
	io:format("~n"),
	inner_loop(N).

Euphoria

 
for i = 1 to 5 do
    for j = 1 to i do
        puts(1, "*") -- Same as "puts(1, {'*'})"
    end for
    puts(1, "\n") -- Same as "puts(1, {'\n'})"
end for
 

puts() is a function that takes two arguments; an integer and a sequence. Strings are simply sequences; there is no string type. The integer specifies where to put the "string". 0 = STDIN, 1 = STDOUT, 2 = STDERR, 3+ = files that are opened with the open() function. puts() prints the sequence out, as a "string". Each element in the sequence provided is printed out as the character with that value in the ASCII character chart.

FALSE

1[$6-][$[$]["*"1-]#%"
"1+]#%

Factor

5 [1,b] [ [ "*" write ] times nl ] each

Fantom

Using for loops:

 
class ForLoops
{
  public static Void main ()
  {
    for (Int i := 1; i <= 5; ++i)
    {
      for (Int j := 1; j <= i; ++j)
      {
         Env.cur.out.print ("*")
      }
      Env.cur.out.printLine ("")
    }
  }
}
 

Using range objects:

 
class ForLoops
{
  public static Void main ()
  {
    (1..5).each |i|
    {
      (1..i).each |j|
      {
         Env.cur.out.print ("*")
      }
      Env.cur.out.printLine ("")
    }
  }
}
 

Forth

: triangle ( n -- )
  1+ 1 do
    cr i 0 do [char] * emit loop
  loop ;
5 triangle

One more:

 
: limit_example
        15 1 do r> r@ dup rot >r drop \ Bring limit on stack
                . \ And print it
        loop ;
\ Gforth and JSForth all work, SP-Forth brakes (different 'for' implementation?)
 

Fortran

Works with: Fortran version 77 and later

C     WARNING: This program is not valid ANSI FORTRAN 77 code. It uses
C     one nonstandard character on the line labelled 5001. Many F77
C     compilers should be okay with it, but it is *not* standard.
      PROGRAM FORLOOP
        INTEGER I, J
 
        DO 20 I = 1, 5
          DO 10 J = 1, I
C           Print the asterisk.
            WRITE (*,5001) '*'
   10     CONTINUE
C         Print a newline.
          WRITE (*,5000) ''
   20   CONTINUE
 
        STOP
 
 5000   FORMAT (A)
C       Standard FORTRAN 77 is completely incapable of completing a
C       WRITE statement without printing a newline. If you wanted to
C       write this program in valid F77, you would have to come up with
C       a creative way of printing varying numbers of asterisks in a
C       single write statement.
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 (A, $)
C5001   FORMAT (A, ADVANCE='NO')
      END

Works with: Fortran version 90 and later

DO i = 1, 5
  DO j = 1, i
    WRITE(*, "(A)", ADVANCE="NO") "*"
  END DO
  WRITE(*,*)
END DO

Fortran 95 (and later) has also a loop structure that can be used only when the result is independent from real order of execution of the loop.

Works with: Fortran version 95 and later

integer :: i
integer, dimension(10) :: v
 
forall (i=1:size(v)) v(i) = i

F#

#light
[<EntryPoint>]
let main args =
    for i = 1 to 5 do
        for j = 1 to i do
            printf "*"
        printfn ""
    0

Gambas

for i = 1 to 5
   for j = 1 to i
      print "*";
   next
   print
next

GAP

for i in [1 .. 5] do
    for j in [1 .. i] do
        Print("*");
    od;
    Print("\n");
od;
 
# *
# **
# ***
# ****
# *****

GML

pattern = ""
for(i = 1; i <= 5; i += 1)
    {
    for(j = 1; j <= i; j += 1)
        {
        pattern += "*"
        }
    pattern += "#"
    }
show_message(pattern)

Go

package main
 
import "fmt"
 
func main() {
    for i := 1; i <= 5; i++ {
        for j := 1; j <= i; j++ {
            fmt.Printf("*")
        }
        fmt.Printf("\n")
    }
}

Output:

*
**
***
****
*****

Groovy

Solution:

for(i in (1..6)) {
    for(j in (1..i)) {
        print '*'
    }
    println ()
}

GW-BASIC

10 FOR I = 1 TO 5
20 FOR J = 1 TO I
30 PRINT "*";
40 NEXT J
50 PRINT
60 NEXT I
 

Haxe

for (i in 1...6) {
	for(j in 0...i) {
		Sys.print('*');
	}
	Sys.println(''); 
}

Haskell

import Control.Monad
 
main = do
  forM_ [1..5] $ \i -> do
    forM_ [1..i] $ \j -> do
      putChar '*'
    putChar '\n'

But it's more Haskellish to do this without loops:

import Data.List (inits)
 
main = mapM_ putStrLn $ tail $ inits $ replicate 5 '*'

HicEst

DO i = 1, 5
  DO j = 1, i
    WRITE(APPend) "*"
  ENDDO
  WRITE() ' '
ENDDO

Icon and Unicon

Icon

procedure main()
every i := 1 to 5 do {
   every 1 to i do
      writes("*")
   write()
   }
end

Unicon

The Icon solution works in Unicon.

Inform 7

repeat with length running from 1 to 5:
	repeat with N running from 1 to length:
		say "*";
	say line break;

IWBASIC

 
OPENCONSOLE
 
FOR X=1 TO 5
 
    FOR Y=1 TO X
 
    LOCATE X,Y:PRINT"*"
 
    NEXT Y
 
NEXT X
 
PRINT
 
CLOSECONSOLE
 
END
 
'Could also have been written the same way as the Creative Basic example, with no LOCATE command.
 

J

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

  ]\ '*****'

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
        for_i. 1 + i. y do.
             z =. ''
 
             for. 1 + i. i do.
                  z=. z,'*'
             end. 
 
             z 1!:2 ] 2 
         end.
 
        i.0 0
   )

But you would almost never see J code like this.

Java

for (int i = 0; i < 5; i++) {
   for (int j = 0; j <= i; j++) {
      System.out.print("*");
   }
   System.out.println();
}

JavaScript

var i, j;
for (i = 1; i <= 5; i += 1) {
  s = '';
  for (j = 0; j < i; j += 1)
    s += '*';
  document.write(s + '<br>');
}

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

: cr  "\n" . ;      : dip  swap '_ set execute _ ;
: nip  swap drop ;  : last  -1 extract nip ;
: times
    swap iota '_ set
    do   dup 'execute dip _ last 0 == if break then
    loop drop ;
 
: concat  "" join ;
'* 1 5 "2dup reshape concat . cr 1 +" times

Liberty BASIC

Unlike some BASICs, Liberty BASIC does not require that the counter variable be specified with 'next'.

for i = 1 to 5
    for j = 1 to i
        print "*";
    next
    print
next
 

Lisaac

1.to 5 do { i : INTEGER;
  1.to i do { dummy : INTEGER;
    '*'.print;
  };
  '\n'.print;
};

Logo

for [i 1 5] [repeat :i [type "*] (print)]
repeat 5 [repeat repcount [type "*] (print)]

Lua

 
for i=1,5 do
  for j=1,i do
    io.write("*")
  end
  io.write("\n")
end
 

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',`1',`5',`1',
   `for(`y',`1',x,`1',
      `*')
')

make

Works with: BSD make

Library: jot

all: line-5
 
ILIST != jot 5
.for I in $(ILIST)
 
line-$(I): asterisk-$(I)-$(I)
	@echo
 
JLIST != jot $(I)
. for J in $(JLIST)
 
.  if "$(J)" == "1"
.   if "$(I)" == "1"
asterisk-1-1:
.   else
IM != expr $(I) - 1
asterisk-$(I)-1: line-$(IM)
.   endif
.  else
JM != expr $(J) - 1
asterisk-$(I)-$(J): asterisk-$(I)-$(JM)
.  endif
	@printf \*
 
. endfor
.endfor

Maple

> for i to 5 do to i do printf( "*" ) end; printf( "\n" ) end;
*
**
***
****
*****

Mathematica

n=5;
For[i=1,i<=5,i++,
 string="";
 For[j=1,j<=i,j++,string=string<>"*"];
 Print[string]
]

MATLAB / Octave

for i = (1:5)
    output = [];
    for j = (1:i)
        output = [output '*'];
    end
    disp(output);
end

Vectorized version:

for i = (1:5)
    disp(repmat('*',1,i));
end

Maxima

for i thru 5 do (
   s: "",
   thru i do s: sconcat(s, "*"),
   print(s)
);

MAXScript

for i in 1 to 5 do
(
    line = ""
    for j in 1 to i do
    (
        line += "*"
    )
    format "%\n" line
)

Mercury

:- module loops_for.
:- interface.
 
:- import_module io.
:- pred main(io::di, io::uo) is det.
 
:- implementation.
:- import_module int.
 
main(!IO) :-
   int.fold_up(outer_loop_body, 1, 5, !IO).
 
:- pred outer_loop_body(int::in, io::di, io::uo) is det.
 
outer_loop_body(I, !IO) :-
   int.fold_up(inner_loop_body, 1, I, !IO),
   io.nl(!IO).
 
:- pred inner_loop_body(int::in, io::di, io::uo) is det.
 
inner_loop_body(_, !IO) :-
   io.write_char('*', !IO).

Modula-2

MODULE For;
  IMPORT InOut;
 
  VAR
    i, j: INTEGER;
 
BEGIN
  FOR i := 1 TO 5 DO
    FOR j := 1 TO i DO
      InOut.Write('*');
    END;
    InOut.WriteLn
  END
END For.

Modula-3

MODULE Stars EXPORTS Main;
 
IMPORT IO;
 
BEGIN
  FOR i := 1 TO 5 DO
    FOR j := 1 TO i DO
      IO.Put("*");
    END;
    IO.Put("\n");
  END;
END Stars.

MOO

for i in [1..5]
  s = "";
  for j in [1..i]
    s += "*";
  endfor
  player:tell(s);
endfor

MUMPS

Routine

FORLOOP
 NEW I,J
 FOR I=1:1:5 DO
 .FOR J=1:1:I DO
 ..WRITE "*"
 .WRITE !
 QUIT

Output:

USER>D FORLOOP^ROSETTA
*
**
***
****
*****

One line

The if statement has to follow the write, or else the if statement would control the write (5 lines with one asterisk each).

FOR I=1:1:5 FOR J=1:1:I WRITE "*" IF J=I W !

Nemerle

for (int i = 0; i < 5; i++)
{
    for (int j = 0; j <= i; j++)
    {
        Write("*");
    }
    WriteLine();
}

NetRexx

/* NetRexx */
options replace format comments java crossref savelog symbols nobinary
 
  say
  say 'Loops/For'
 
  loop i_ = 1 to 5
    loop for i_
      say '*\-'
      end
    say
    end i_
 

NewLISP

 
(for (i 1 5)
  (for(j 1 i)
    (print "*"))
  (print "\n"))
 

Nimrod

for i in 1..5:
  for i in 1..i:
    stdout.write("*")
  echo("")

Objeck

 
bundle Default {
  class For {
    function : Main(args : String[]) ~ Nil {
      DoFor();
    }
 
    function : native : DoFor() ~ Nil {
    	for (i := 0; i < 5; i += 1;) {
          for (j := 0; j <= i; j += 1;) {
            "*"->Print();
          };
          ""->PrintLine();	
       };
    }
  }
}
 

OCaml

for i = 1 to 5 do
  for j = 1 to i do
    print_string "*"
  done;
  print_newline ()
done

Octave

for i = 0:1:4
  for j = 0:1:i
    printf("*");
  endfor
  printf("\n");
endfor

Order

#include <order/interpreter.h>
 
ORDER_PP(
  8for_each_in_range(8fn(8I,
                         8print(
                           8for_each_in_range(8fn(8J, 8print((*))),
                                              1, 8plus(8I, 1))
                           8space)),
                         1, 6)
)

(Order cannot print newlines, so this example just uses a space.)

Oz

for I in 1..5 do
   for _ in 1..I do
      {System.printInfo "*"}
   end
   {System.showInfo ""}
end

Note: we don't use the inner loop variable, so we prefer not to give it a name.

Panoramic

 
dim x,y
 
for x=1 to 5
 
    for y=1 to x
 
    print "*";
 
    next y
 
print
 
next x
 

PARI/GP

for(a=1,5,for(b=1,a,print1("*"));print())

Pascal

program stars(output);
 
var
  i, j: integer;
 
begin
  for i := 1 to 5 do
    begin
      for j := 1 to i do
        write('*');
      writeln
    end
end.

Perl

for ($x = 1; $x <= 5; $x++) {
  for ($y = 1; $y <= $x; $y++) {
    print "*";
  } 
  print "\n";
}

foreach (1..5) {
  foreach (1..$_) {
    print '*';
  }
  print "\n";
}

However, if we lift the constraint of two loops the code will be simpler:

print ('*' x $_ . "\n") for 1..5

Perl 6

Works with: Rakudo version #22 "Thousand Oaks"

for ^5 {
 
	for 0..$_ {
		print "*";
	}
 
	print "\n";
 
}

or using only one for loop:

say '*' x $_ for 1..5;

or without using any loops at all:

([\~] "*" xx 5).join("\n").say;

PHP

for ($i = 1; $i <= 5; $i++) {
  for ($j = 1; $j <= $i; $j++) {
    echo '*';
  }
  echo "\n";
}

or

foreach (range(1, 5) as $i) {
  foreach (range(1, $i) as $j) {
    echo '*';
  }
  echo "\n";
}

PicoLisp

(for N 5
   (do N (prin "*"))
   (prinl) )

Pike

int main(){
   for(int i = 1; i <= 5; i++){
      for(int j=1; j <= i; j++){
         write("*");
      }
      write("\n");
   }
}

PL/I

 
do i = 1 to 5;
   put skip edit (('*' do j = 1 to i)) (a);
end;
 

Pop11

lvars i, j;
for i from 1 to 5 do
    for j from 1 to i do
        printf('*','%p');
    endfor;
    printf('\n')
endfor;

PowerShell

for ($i = 1; $i -le 5; $i++) {
    for ($j = 1; $j -le $i; $j++) {
        Write-Host -NoNewline *
    }
    Write-Host
}

Alternatively the same can be achieved with a slightly different way by using the range operator along with the ForEach-Object cmdlet:

1..5 | ForEach-Object {
    1..$_ | ForEach-Object {
        Write-Host -NoNewline *
    }
    Write-Host
}

while the inner loop wouldn't strictly be necessary and can be replaced with simply "*" * $_.

PureBasic

If OpenConsole()
  Define i, j
  For i=1 To 5
    For j=1 To i
      Print("*")
    Next j
    PrintN("")
  Next i
  Print(#LFCR$+"Press ENTER to quit"): Input()
  CloseConsole()
EndIf

Python

import sys
for i in xrange(5):
    for j in xrange(i+1):
        sys.stdout.write("*")
    print

Note that we have a constraint to use two for loops, which leads to non-idiomatic Python. If that constraint is dropped we can use the following, more idiomatic Python solution:

for i in range(1,6):
    print '*' * i

R

for(i in 0:4) {
  s <- ""
  for(j in 0:i) {
    s <- paste(s, "*", sep="")
  }
  print(s)
}

Racket

(for ([i (in-range 1 6)]) (for ([j i]) (display "*")) (newline))

REBOL

; Use 'repeat' when an index required, 'loop' when repetition suffices:
 
repeat i 5 [
	loop i [prin "*"] 
	print ""
]
 
; or a more traditional for loop:
 
for i 1 5 1 [
	loop i [prin "*"]
	print ""
]

REXX

version 1

  do i=1 to 5
  s=''
           do j=1 to i
           s=s || '*'
           end
  say s
  end

version 2

  do i=1 for 5
  s=''
         do i
         s=s'*'
         end
  say s
  end

Retro

6 [ 0; cr [ '* emit ] times ] iter

Ruby

One can write a for loop as for i in 1..5; ...end or as for i in 1..5 do ... end or as (1..5).each do |i| ... end. All three forms call Range#each to iterate 1..5.

for i in 1..5
   for j in 1..i
      print "*"
   end
   puts
end

Ruby has other ways to code these loops; Integer#upto is most convenient.

Integer#upto	Integer#times	Kernel#loop
1.upto(5) do |i| 1.upto(i) do |j| print "*" end puts end	5.times do |i| # i goes from 0 to 4 (i+1).times do print "*" end puts end	i = 1 loop do j = 1 loop do print "*" break if (j += 1) > i end puts break if (i += 1) > 5 end

Or we can use String#* as the inner loop, and Enumerable#map as the outer loop. This shrinks the program to one line.

puts (1..5).map { |i| "*" * i }

Salmon

iterate (x; [0...4])
  {
    iterate (y; [0...x])
        print("*");;
    print("\n");
  };

or

for (x; 0; x < 5)
  {
    for (y; 0; y <= x)
        print("*");;
    print("\n");
  };

SAS

data _null_;
length a $5;
do n=1 to 5;
  a="*";
  do i=2 to n;
    a=trim(a) !! "*";
  end;
  put a;
end;
run;

Sather

Sather allows the definition of new iterators. Here's we define for! so that it resembles the known for in other languages, even though the upto! built-in can be used.

class MAIN is
  -- from, to, step
  for!(once init:INT, once to:INT, once inc:INT):INT is
    i ::= init;
    loop while!( i <= to );
      yield i;
      i := i + inc;
    end;
  end;
 
  main is
    i, j :INT;
    loop i := for!(1, 5, 1);   -- 1.upto!(5)
      loop j := for!(1, i, 1); -- 1.upto!(i)
        #OUT + "*";
      end;
      #OUT + "\n";
    end;
  end;
end;
 

Scheme

(do ((i 1 (+ i 1)))
    ((> i 5))
    (do ((j 1 (+ j 1)))
        ((> j i))
        (display "*"))
    (newline))

Seed7

for I range 1 to 5 do
  for J range 1 to I do
    write("*");
  end for;
  writeln;
end for;

Slate

1 to: 5 do: [| :n | inform: ($* repeatedTimes: n)].

Scala

for (i <- 1 to 5) {
    for (j <- 1 to i)
        print("*")
    println
}

Smalltalk

1 to: 5 do: [ :aNumber |
  aNumber timesRepeat: [ '*' display ].
  Character nl display.
]

or:

1 to: 5 do: [ :row |
  1 to: row do: [:col | '*' display ].
]

(only for demonstration of nested for-loops; as the column is not needed, the first solution is probably clearer).

However, streams already have some builtin repetition mechanism, so a programmer might write:

Works with: Smalltalk/X

1 to: 5 do: [ :n |
  Stdout next: n put: $*; cr
]

SNOBOL4

A slightly longer, "mundane" version

ol	outer = ?lt(outer,5) outer + 1	:f(end)
	inner = outer; stars = ""
il	stars = ?gt(inner,0) stars "*"	:f(disp)
	inner = inner - 1	:(il)
disp	output = stars;	:(ol)
end

The "real SNOBOL4" starts here:

outer	b = a = ?lt(a,5) a + 1	:f(end)
inner	t = t ?(b = (gt(b,0) b - 1)) "*"	:s(inner)
	t span("*") . terminal = 	:(outer)
end

one "loop" only:

	a = "*****"; 
a	a len(x = x + 1) . output	:s(a)
end

... or just (courtesy of GEP2):

Works with: SNOBOL4 version which defaults to anchored mode

        "*****" arb $ output fail
end

Suneido

for(i = 0; i < 5; ++i)
    {
    str = ''
    for (j = 0; j <= i; ++j)
        str $= '*'
    Print(str)
    }

Tcl

for {set lines 1} {$lines <= 5} {incr lines} {
    for {set i 1} {$i <= $lines} {incr i} {
        puts -nonewline "*"
    }
    puts ""
}

Note that it would be more normal to produce this output with:

for {set i 1} {$i <= 5} {incr i} {
    puts [string repeat "*" $i]
}

It bears noting that the three parts of the for loop do not have to consist of "initialize variable", "test value of variable" and "increment variable". This is a common way to think of it as it resembles the "for" loop in other languages, but many other things make sense. For example this for-loop will read a file line-by-line:

set line ""
for { set io [open test.txt r] } { ![eof $io] } { gets $io line } {
    if { $line != "" } { ...do something here... }
}

(This is a somewhat awkward example; just to show what is possible)

TI-89 BASIC

Local i,j
ClrIO
For i, 1, 5
  For j, 1, i
    Output i*8, j*6, "*"
  EndFor
EndFor

TorqueScript

for(%i = 0; %i < 5; %i++)
{
    for(%x = %i; %x < 5; %x++)
    {
        %string = %string @ "*";
        echo(%string);
    }
}

TUSCRIPT

 
$$ MODE TUSCRIPT
m=""
LOOP n=1,5
 m=APPEND (m,"","*")
 PRINT m
ENDLOOP
 

Output:

*
**
***
****
***** 

UNIX Shell

A conditional loop, using a while control construct, can have the same effect as a for loop. (The original Bourne Shell has no echo -n "*", so this uses printf "*".)

Works with: Bourne Shell

#!/bin/sh
# Using a while control construct to emulate a for loop
 
l="1"                   # Set the counters to one
while [ "$l" -le 5 ]    # Loop while the counter is less than five
  do
  m="1"
  while [ "$m" -le "$l" ]  # Loop while the counter is less than five
    do
    printf "*"
    m=`expr "$m" + 1`   # Increment the inner counter
  done
  echo
  l=`expr "$l" + 1`   # Increment the outer counter
done

The Bourne Shell has a for loop, but it requires a list of words to iterate. The jot(1) command from BSD can output an appropriate list of numbers.

Works with: Bourne Shell

Library: jot

for i in `jot 5`; do
	for j in `jot $i`; do
		printf \*
	done
	echo
done

Bash has for loops that act like C. These loops are very good for this task.

Works with: Bourne Again SHell version 3

for (( x=1; $x<=5; x=$x+1 )); do 
  for (( y=1; y<=$x; y=$y+1 )); do 
    echo -n '*'
  done
  echo ""
done

C Shell

Library: jot

foreach i (`jot 5`)
	foreach j (`jot $i`)
		echo -n \*
	end
	echo ""
end

UnixPipes

yes \ | cat -n | (while read n ; do
  [ $n -gt 5 ] && exit 0;
  yes \* | head -n $n | xargs -n $n echo
done)

Vedit macro language

for (#1 = 1; #1 <= 5; #1++) {
    for (#2 = 1; #2 <= #1; #2++) {
        Type_Char('*')
    }
    Type_Newline
}

Visual Basic

'This Prints to the Debug-Window!
Dim i As Integer
Dim ii As Integer
Dim x As Integer
Dim out As String
 
output = ""
 
For i = 1 To 5
    For ii = 1 To i
        out = out + "*"
    Next ii
    Debug.Print (out)
    out = ""
Next i

Visual Basic .NET

Works with: Visual Basic version 2002

For x As Integer = 0 To 4
    For y As Integer = 0 To x
        Console.Write("*")
    Next
    Console.WriteLine()
Next

XPL0

code ChOut=8, CrLf=9;
int I, J;
for I:= 1 to 5 do
    [for J:= 1 to I do
        ChOut(0, ^*);
    CrLf(0);
    ]