Loops/For

“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.

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:

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

Related tasks

Reference

For loop Wikipedia.

11l

Translation of: Python

L(i) 1..5
   L 1..i
      print(‘*’, end' ‘’)
   print()

Pythonic solution:

L(i) 1..5
   print(‘*’ * i)

68000 Assembly

Although it's more natural for the language to loop downward rather than forward, both are possible.

main:
     MOVEQ #1,D1           ;counter for how many times to print *, this is also the loop counter
.outerloop:
     MOVE.W D1,D2
     SUBQ.W #1,D2
.innerloop:
     MOVE.B #'*',D0
     JSR PrintChar         ;hardware-dependent printing routine
DBRA D2,.innerloop         ;DBRA loops until wraparound to $FFFF, which is why we subtracted 1 from D2 earlier.
     JSR NewLine           ;hardware-dependent newline routine
     ADDQ.W #1,D1
     CMP.W #6,D1           ;are we done yet?
     BCS .outerloop        ;if not, go back to the top
     RTS

8086 Assembly

The following works with MS-DOS. Called as a subroutine (i.e. "call StarSub")

StarSub:

mov ah,02h  ;needed to prime the interrupt command for printing to screen
mov ch,1    ;outer loop counter

outer_loop:
mov cl,ch   ;refresh the inner loop counter, by copying the value of the outer loop counter to it.
            ;each time the inner loop finishes, it will last one iteration longer the next time.

inner_loop:
mov dl,02Ah ;ascii for *
int 21h     ;tells DOS to print the contents of dl to the screen
dec cl
jnz inner_loop
mov dl,13   ;Carriage Return
int 21h
mov dl,10   ;New Line
int 21h

inc ch      ;make the outer loop counter bigger for next time.
cmp ch,5
jnz outer_loop

ret

This illustrates two kinds of 'for' loop. The first kind is "loop", which iterates from the low to the high value, and passes the current loop index as a parameter to the inner word. The second is 'times', which takes a count and repeats the word that many times.

( ( '* putc ) swap times cr ) 1 5 loop

AArch64 Assembly

Works with: as version Raspberry Pi 3B version Buster 64 bits

/* ARM assembly AARCH64 Raspberry PI 3B */
/*  program loop64.s   */
 
/*******************************************/
/* Constantes file                         */
/*******************************************/
/* for this file see task include a file in language AArch64 assembly*/
.include "../includeConstantesARM64.inc"
/*******************************************/
/* Initialized data                        */
/*******************************************/
.data
szMessX: .asciz "X"
szCarriageReturn:  .asciz "\n"
/*******************************************/
/* UnInitialized data                      */
/*******************************************/
.bss 
/*******************************************/
/*  code section                           */
/*******************************************/
.text
.global main 
main:                     // entry of program
 
    mov x2,0              // counter loop 1
1:                        // loop start 1
    mov x1,0              // counter loop 2
2:                        // loop start 2
    ldr x0,qAdrszMessX
    bl affichageMess
    add x1,x1,1           // x1 + 1
    cmp x1,x2             // compare x1 x2
    ble 2b                // loop label 2 before
    ldr x0,qAdrszCarriageReturn   
    bl affichageMess
    add x2,x2,1           // x2 + 1
    cmp x2,#5             // for five loop
    blt 1b                // loop label 1 before
 

100:                      // standard end of the program */
    mov x0,0              // return code
    mov x8,EXIT           // request to exit program
    svc 0                 // perform the system call
 
qAdrszMessX:           .quad szMessX
qAdrszCarriageReturn:  .quad  szCarriageReturn
/********************************************************/
/*        File Include fonctions                        */
/********************************************************/
/* for this file see task include a file in language AArch64 assembly */
.include "../includeARM64.inc"

Action!

Proc Main()
byte I,J

 For I=1 to 5
  Do
   For J=1 to I
    Do
     Print("*")
    Od
   PrintE("")
  Od

Return

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;

Agena

Tested with Agena 2.9.5 Win32

for i to 5 do
    for j to i do
        write( "*" )
    od;
    print()
od

ALGOL 60

INTEGER I,J;
FOR I:=1 STEP 1 UNTIL 5 DO
BEGIN 
   FOR J:=1 STEP 1 UNTIL I DO
      OUTTEXT("*");
   OUTLINE
END

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:

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

ALGOL W

In Algol W, write starts a new line, writeon continues it.

begin
    for i := 1 until 5 do
    begin
        write( "*" );
        for j := 2 until i do
        begin
            writeon( "*" )
        end j
    end i
end.

ALGOL-M

BEGIN
    INTEGER I, J;
    FOR I := 1 STEP 1 UNTIL 5 DO
    BEGIN
        WRITE( "" );
        FOR J := 1 STEP 1 UNTIL I DO
            WRITEON( "*" );
    END;
END

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

Apex

for (Integer i = 0; i < 5; i++) {
    String line = '';

    for (Integer j = 0; j < i; j++) {
        line += '*';
    }

    System.debug(line);
}

List<String> lines = new List<String> {
    '*',
    '**',
    '***',
    '****',
    '*****'
};

for (String line : lines) {
    System.debug(line);
}

APL

For most purposes, the APL analogue of a for loop is the each operator ¨. The most natural way to accomplish this task doesn't use a nested each, but the repeat operator / inside a single each:

stars ← { ⍵ 1 ⍴ {⍵/'*'}¨⍳⍵ }

To stick to the letter of the task description, we can nest an each inside another one, but it's a little silly. Plus not all dialects support niladic dfns, so the innermost "return one star" function has to take a dummy argument:

stars ← { ⍵ 1 ⍴ { {1⌷'*',⍵} ¨ ⍳⍵ } ¨ ⍳⍵ }

Additionally, Dyalog and some other dialects support the more traditional structured programming controls inside a named function definition (tradfn):

Works with: Dyalog APL

∇result ← stars count; i; j; vec
 vec ← ⍬
 :for i :in ⍳ count
   vec ,← ⊂''
   :for j :in ⍳ i
     vec[i],←'*'
   :endfor
:endfor
result ← count 1 ⍴ vec
∇

Output:

The result of all three implementations of stars is a column vector, which is displayed like this:

      stars 5
*
**
***
****
*****

AppleScript

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

Output:

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

ARM Assembly

Works with: as version Raspberry Pi

/* ARM assembly Raspberry PI  */
/*  program loop1.s   */

/* Constantes    */
.equ STDOUT, 1     @ Linux output console
.equ EXIT,   1     @ Linux syscall
.equ WRITE,  4     @ Linux syscall
/* Initialized data */
.data
szMessX: .asciz "X"
szCarriageReturn:  .asciz "\n"

/* UnInitialized data */
.bss 

/*  code section */
.text
.global main 
main:                /* entry of program  */
    push {fp,lr}    /* saves 2 registers */

    mov r2,#0       @ counter loop 1
1:       @ loop start 1
    mov r1,#0        @ counter loop 2
2:       @ loop start 2
    ldr r0,iAdrszMessX
    bl affichageMess
    add r1,#1       @ r1 + 1
    cmp r1,r2       @ compare r1 r2
    ble 2b        @ loop label 2 before
    ldr r0,iAdrszCarriageReturn   
    bl affichageMess
    add r2,#1       @ r2 + 1
    cmp r2,#5       @ for five loop
    blt 1b         @ loop label 1 before


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

iAdrszMessX:  .int szMessX
iAdrszCarriageReturn:  .int  szCarriageReturn
/******************************************************************/
/*     display text with size calculation                         */ 
/******************************************************************/
/* r0 contains the address of the message */
affichageMess:
    push {fp,lr}    			/* save  registres */ 
    push {r0,r1,r2,r7}    		/* save others registers */
    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 */
    addne r2,r2,#1   			/* else add 1 in the length */
    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" */
    swi #0                      /* call systeme */
    pop {r0,r1,r2,r7}     		/* restaur others registers */
    pop {fp,lr}    				/* restaur des  2 registres */ 
    bx lr	        			/* return  */

Arturo

loop 0..5 'x [
	loop 0..x 'y [
		prints "*"
	]
	print ""
]

Output:

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

Asymptote

Asymptote's control structures are similar to those in C, C++, or Java

for(int i = 0; i < 6; ++i) {
  for(int j = 0; j < i; ++j) {
    write("*", suffix=none);
  }
    write("");
}

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

Avail

For each row from 1 to 5 do
[
    For each length from 1 to row do [Print: "*";];
    Print: "\n";
];

Since the inner loop index is unneeded, it may be more natural to use the From_to_do_ loop format:

For each row from 1 to 5 do
[
    From 1 to row do [Print: "*";];
    Print: "\n";
];

AWK

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

Axe

In this example, the Axe code is nearly identical to the TI-83 BASIC version. However, note the swapped order of the I and J in the Output() statement. Also, unlike TI-83 BASIC, Axe does not support an increment value other than 1.

ClrHome
For(I,1,5)
For(J,1,I)
Output(J,I,"*")
End
End

Babel

((main { 10 star_triangle ! })

(star_triangle { 
    dup
    <- 
    { dup { "*" << } <-> 
            iter - 1 + 
        times 
        "\n" << } 
    -> 
    times }))

Output:

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

The key operator here is 'iter' which gives the current iteration of the loop body it resides in. When used with the 'times' operator, it generates a countdown.

Bait

const ROWS := 5

fun main() {
	for i := 1; i <= ROWS; i += 1 {
		for j := 1; j <= i; j += 1 {
			print('*')
		}
		println('')
	}
}

bash

for i in {1..5}
do
  for ((j=1; j<=i; j++));
  do
    echo -n "*"
  done
  echo
done

BASIC

Works with: QuickBasic version 4.5

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

Applesoft BASIC

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

BASIC256

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

BaCon

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

BBC BASIC

Works with: BBC BASIC for Windows

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

Chipmunk Basic

Works with: Chipmunk Basic version 3.6.4

10 for i = 1 to 5
20  for j = 1 to i
30   print "*";
40  next j
50  print
60 next i

Commodore BASIC

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

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

GW-BASIC

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

FBSL

#APPTYPE CONSOLE
FOR dim i = 1 TO 5
    FOR dim j = 1 TO i
        PRINT "*"; 
    NEXT j   
    PRINT
NEXT i
Pause

Output:

*
**
***
****
*****
Press any key to continue...

FUZE BASIC

FOR n = 1 to 5 CYCLE
    FOR k = 1 to n CYCLE
        print "*";
    REPEAT
    PRINT
REPEAT
END

IS-BASIC

100 FOR I=1 TO 5
110   FOR J=1 TO I
120     PRINT "*";
130   NEXT
140   PRINT
150 NEXT

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.

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

MSX Basic

The GW-BASIC solution works without any changes.

Microsoft Small Basic

For i = 1 To 5 
  For j = 1 To i
    TextWindow.Write("*")
  EndFor
  TextWindow.WriteLine("")
EndFor

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

QBasic

The GW-BASIC solution works without any changes. Also The BASIC256 solution works without any changes.

Quite BASIC

The GW-BASIC solution works without any changes.

Run BASIC

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

SmallBASIC

for a = 1 to 5
  for b = 1 to a
    print "*";
  next
  print
next

smart BASIC

While some versions of BASIC allow for NEXT without a variable, smart BASIC requires the variable designation.

for n = 1 to 5
    for m = 1 to n
        print "*";
    next m
    print
next n

True BASIC

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

Visual Basic

Works with: VB6

Public OutConsole As Scripting.TextStream
For i = 0 To 4
    For j = 0 To i
        OutConsole.Write "*"
    Next j 
    OutConsole.WriteLine
Next i

Visual Basic .NET

Works with: Visual Basic .Net 2002

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

Yabasic

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

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

bc

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

BCPL

get "libhdr"

let start() be
    for i = 1 to 5
    $(  for j = 1 to i do wrch('**')
        wrch('*N')
    $)

Befunge

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

Binary Lambda Calculus

The following 22-byte BLC program is generated from https://github.com/tromp/AIT/blob/master/rosetta/forloops.lam :

18 18 11 50 73 9c e7 40 b3 df cb df 38 1c bd a3 88 05 bb 00 2a 0a

blz

for i = 1; i <= 5; i++
    line = ""
    for (j = 1; j <= i; j++)
        line = line + "*"
    end
    print(line)
end

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#

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();
        }
    }
}

C++

for(int i = 0; i < 5; ++i) {
  for(int j = 0; j < i; ++j)
    std::cout.put('*');

  std::cout.put('\n');
}

C3

for (int i = 0; i < 5; i++)
{
  for (int j = 1; j <= i; j++) io::print("*");
  io::printn("*");
}

Ceylon

shared void run() {
	
	for(i in 1..5) {
		for(j in 1..i) {
			process.write("*");
		}
		print("");
	}
}

Chapel

for i in 1..5 {
        for 1..i do write('*');
        writeln();
}

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.

Clojure

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

CLU

start_up = proc ()
    po: stream := stream$primary_output()
    
    for i: int in int$from_to(1, 5) do
        for j: int in int$from_to(1, i) do
            stream$putc(po, '*')
        end
        stream$putl(po, "")
    end
end start_up

COBOL

       IDENTIFICATION DIVISION.
       PROGRAM-ID. Display-Triangle.

       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  Outer-Counter PIC 9.
       01  Inner-Counter PIC 9. 

       PROCEDURE DIVISION.
       PERFORM VARYING Outer-Counter FROM 1 BY 1 UNTIL 5 < Outer-Counter

           PERFORM VARYING Inner-Counter FROM 1 BY 1
                   UNTIL Outer-Counter < Inner-Counter
               DISPLAY "*" NO ADVANCING
           END-PERFORM

           DISPLAY "" *> Output a newline
       END-PERFORM

       GOBACK
       .

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 #\*))
  (terpri))

or

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

or

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

or

(use-package :iterate)
(iter
  (for i from 1 to 5)
    (iter
      (for j from 1 to i)
      (princ #\*))
    (terpri))

Coq

Section FOR.
  Variable T : Type.
  Variable body : nat -> T -> T.
  Variable start : nat.

  Fixpoint for_loop n : T -> T :=
    match n with
    | O => fun s => s
    | S n' => fun s => for_loop n' (body (start + n') s)
    end.

End FOR.

Eval vm_compute in
  for_loop _
    (fun i =>
      cons
        (for_loop _
          (fun j => cons tt)
          0 (S i) nil
        )
    )
    0 5 nil.

Cowgol

include "cowgol.coh";

var i: uint8 := 1;
while i <= 5 loop
    var j: uint8 := 1;
    while j <= i loop
        print_char('*');
        j := j + 1;
    end loop;
    print_nl();
    i := i + 1;
end loop;

Crystal

1.upto(5) do |i|
  1.upto(i) do |j|
    print "*"
  end
  puts
end

Or another way, more succinctly put:

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

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++)
        for (var j = 0; j < i + 1; j++)
            print("*");
        print("\n");
}

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.

Diego

set_ns(rosettacode);

add_var({str},s)_value();
add_var({str},output);

add_for({int},i)_from(1)_uptoand(5)_inc()
    with_var(s)_v();
    add_for({int},j)_from(0)_upto([i])_inc()
        with_var(s)_calc([s]&="*");
    ;
    with_var(output)_calc(&=[s]&\n);
;

me_msg([output]);

reset_ns[];

DMS

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

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()

Draco

proc nonrec main() void:
    byte i,j;
    for i from 1 upto 5 do
        for j from 1 upto i do
            write("*")
        od;
        writeln()
    od 
corp

Output:

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

Dragon

for (i = 0, i < 5, i++) {
   for (j = 0, j <= i, j++) {
      show "*"
   }
   showln ""
}

DWScript

var i, j : Integer;

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

Dyalect

Translation of: Swift

for i in 1..5 {
    for _ in 1..i {
        print("*", terminator: "")
    }
    print()
}

Output:

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

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.)

EasyLang

for i = 1 to 5
  for j = 1 to i
    write "*"
  .
  print ""
.

Ed

Uses unary i-encoded numbers for state and turns them into asterisks before printing.

H
a
iiiii
.
s/\B/\
/g
a

.
y
d
g/i/x\
s/.*/&*/\
-1d\
y
,p
Q

EDSAC order code

As with many other machine-level languages, there is no inbuilt looping construct; but the equivalent of a FOR or DO loop can easily be synthesized using conditional branching orders and a control variable.

The EDSAC character set does not include a * character, so + has been used instead.

Characters are encoded in five-bit form, with each code point producing a different character depending on whether the machine is in 'letter' or 'figure' mode: this is why it is necessary to output a 'figure shift' control character at the beginning of the job.

[ Loops
  =====
  
  A program for the EDSAC
  
  Demonstrates nested loops
  and printer output
  
  Works with Initial Orders 2 ]



        T56K  [ set load point  ]
        GK    [ set theta       ]
        
        O21@  [ figure shift    ]
        
[  1 ]  T24@  [ a = 0           ]
        A19@  [ a = i           ]
        
[  3 ]  T20@  [ j = a; a = 0    ]
        O22@  [ write character ]
        A20@  [ a = j           ]
        S17@  [ a -= 1          ]
        U20@  [ j = a           ]
        E3@   [ if a>=0 go to 3 ]
        
        O23@  [ write line feed ]
        T24@  [ a = 0           ]
        A19@  [ a = i           ]
        A17@  [ a += 1          ]
        U19@  [ i = a           ]
        S18@  [ a -= 5          ]
        G1@   [ if a<0 go to 1  ]

        ZF    [ halt            ]
        
[ 17 ]  P0D   [ const: 1        ]
[ 18 ]  P2D   [ const: 5        ]
        
[ 19 ]  P0F   [ var: i          ]
[ 20 ]  P0F   [ var: j          ]
        
[ 21 ]  #F    [ figure shift    ]
[ 22 ]  ZF    [ '+' character   ]
[ 23 ]  &F    [ line feed       ]
        
[ 24 ]  P0F   [ used to clear a ]
        
        EZPF  [ begin execution ]

Output:

+
++
+++
++++
+++++

EGL

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

Ela

open monad io

loop m n | n < m = do
            loop' n 0
            putStrLn ""
            loop m (n + 1)
         | else = do return ()
          where loop' m n | n <= m = do
                              putStr "*"
                              loop' m (n + 1)
                          | else = do return ()

_ = loop 10 1 ::: IO

Output:

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

Elena

ELENA 6.x :

import extensions;
 
public program()
{
    for(int i := 0; i < 5; i += 1)
    {
        for(int j := 0; j <= i; j += 1)
            { console.write("*") };
 
        console.writeLine()
    }
}

Output:

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

Elixir

defmodule Loops do
  def loops_for(n) do
    Enum.each(1..n, fn i ->
      Enum.each(1..i, fn _ -> IO.write "*" end)
      IO.puts ""
    end)
  end
end

Loops.loops_for(5)

one line (Comprehensions)

for i <- 1..5, do: IO.puts (for j <- 1..i, do: "*")

Emacs Lisp

;; Lisp implementation of c-for is like:
;; (let ((i nil))
;;   (while (progn (setq i (if (not i) 0 (1+ i) )) ;; if value of i is nil, initialize its value to 0, if else, add 1
;; 		(< i 10))                       ;; end loop when i > 10
;;     (... body ...) ) )                          ;; loop body

(let ((i nil) (str ""))
  (while (progn (setq i (if (not i) 0 (1+ i) ))
		(< i 5))
    (setq str (concat str "*"))
    (message str) ) )

output logged in buffer *Messages*:

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

EMal

for int i = 0; i < 5; ++i
  for int j = 0; j <= i; ++j do write("*") end
  writeLine()
end

Output:

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

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).

ERRE

FOR I=1 TO 5 DO
    FOR J=1 TO I DO
        PRINT("*";)
    END FOR
    PRINT
END FOR

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.

F#

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

Factor

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

FALSE

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

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 ("")
    }
  }
}

Fennel

(for [i 1 4]
  (for [j 1 i]
    (io.write "*"))
  (print))

Fermat

for i = 1 to 5 do for j = 1 to i do !'*'; od; !; od

FOCAL

When the program exits the outer loop, the control variable I is set to 4 + 1 = 5; we can therefore permit execution to fall through into the inner loop for one more iteration.

01.10 FOR I=1,4; DO 2.0

02.10 FOR J=1,I; TYPE "*"
02.20 TYPE !

Output:

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

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

But if one accepts that a do-loop can be expressed without the actual word "do" (or "for"), then

      DO 1 I = 1,5
    1 WRITE (6,*) ("*", J = 1,I)
      END

That is a complete programme, though a more polite source file would have INTEGER I,J. It uses the old-style DO label etc. style of DO-loop to save on having to specify an END DO. The WRITE statement's output list is generated by an "implied" DO-loop having much of the form of DO J = 1,I and is indeed a proper loop. The output item is a text literal, which in earlier Fortran was unknown, however the result can still be achieved:

      DO 1 I = 1,5
    1 WRITE (6,2) (666, J = 1,I)
    2 FORMAT(5I1)
      END

This works because if a value cannot be fitted into its output field, the field is filled with asterisks. Which, is what is wanted! Just allow one digit for output (I1), and present a large integer.

FreeBASIC

' FB 1.05.0 Win64

For i As Integer = 1 To 5
  For j As Integer = 1 To i
    Print "*";
  Next
  Print
Next

Sleep

Output:

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

Frink

for n = 1 to 5
{
   for a = 1 to n
      print["*"]

   println[]
}

Futhark

This example is incorrect. Please fix the code and remove this message.

Details: Futhark's syntax has changed, so this example will not compile

Futhark does not have I/O, so this program simply counts in the inner loop.

fun main(n: int): [n]int =
  loop (a = replicate n 0) = for i < n do
    (loop (s = 0) = for j < i+1 do
     s + j
     let a[i] = s
     in a)
  in a

FutureBasic

window 1

long i, j

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

HandleEvents

Gambas

Click this link to run this code

Public Sub Main()
Dim i, j As Integer

For i = 1 To 5
   For j = 1 To i
      Print "*";
   Next
   Print
Next

End

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

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

100 FOR I=1 TO 5
110 FOR J=1 TO I
120 PRINT "*";
130 NEXT J
140 PRINT
150 NEXT I
160 END

Output:

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

Hack

for($i = 0; $i < 5; $i++) {
    for($j = 0; $j <= $i; $j++) {
        echo '*';
    }
  
    echo '\n';
}

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 '*'

Or, with a list comprehension:

putStrLn $ unlines [replicate n '*' | n <- [1..5]]

Taking from an infinite stream of increasing length lines:

putStrLn . unlines . take 5 $ iterate ('*':) "*"

Haxe

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

hexiscript

for let i 1; i <= 5; i++
  for let j 1; j <= i; j++
    print "*"
  endfor
  println ""
endfor

HicEst

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

HolyC

U8 i, j;
for (i = 1; i <= 5; i++) {
  for (j = 1; j <= i; j++)
    Print("*");
  Print("\n");
}

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;

J

J is array-oriented, so there is very little need for loops. For example:

   ]\ '*****'
*    
**   
***  
**** 
*****

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).

{{
  for_i. i. y do.
    z=. ''
    for. i. i do.
      z=. z,'*'
    end.
    echo z
  end.
  EMPTY
}}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>');
}

Alternatively, using JavaScript's Array.forEach(), and given an array of indices, or a simple range function which generates a range:

function range(i) {
  return i ? range(i - 1).concat(i) : [];
}

range(5) --> [1, 2, 3, 4, 5]

We could write something like:

var s = '';

range(5).forEach(
  function (line) {
    range(line).forEach(
      function () { s += '*'; }
    );
    s += '\n';
  }
);

console.log(s);

but it might be more natural in JavaScript, if we are going to use built-in Array functions, to simplify a little with Array.reduce(), writing:

console.log(
  range(5).reduce(
    function (a, n) {
      return a + Array(n + 1).join('*') + '\n';
    }, ''
  )
);

in which the inner n refers to the Array value visited at the next level out, and the triangle is returned as a single expression, rather than as a series of variable mutations.

Finally, in contexts where an expression composes better than a statement, the effect of a loop can often be expressed as a map.

console.log(
  range(5).map(function(a) {
    return Array(a + 1).join('*');
  }).join('\n')
);

Jinja

Variable usage inside a loop, before version 2.10 :

print(Template("""{% set sum = 0 %}
                  {% for i in range(6) %}
                        {{ sum }}{% set sum = sum + i %}
                  {%- endfor %}""").render())

Since 2.10 :

print(Template("""{% set sum = namespace(value=0) %}
                  {% for i in range(6) %}
                        {{ sum.value }}{% set sum.value = sum.value + i %}
                  {%- endfor %}""").render())

jq

# Single-string version using explicit nested loops:
def demo(m):
  reduce range(0;m) as $i
    (""; reduce range(0;$i) as $j
           (.; . + "*" )  + "\n" ) ;

# Stream of strings:
def demo2(m):
  range(1;m)
  | reduce range(0;.) as $j (""; . + "*");

# Variation of demo2 using an implicit inner loop:
def demo3(m): range(1;m) | "*" * . ;

Example using demo(6)

Output:

$ jq -r -n -f loops_for.jq
*
**
***
****
*****

Jsish

Code from Javascript entry.

var i, j, s;
for (i = 1; i <= 5; i += 1) {
    s = '';
    for (j = 0; j < i; j += 1) s += '*';
    puts(s);
}

Output:

prompt$ jsish forloop.jsi
*
**
***
****
*****

Julia

for i in 1:5
    for j in 1:i
        print("*")
    end
    println()
end

Output:

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

Klong

:" x{p}:*y means repeat {p} x times starting at y "

5{x{.d(0c*);x}:*0;.p("");x+1}:*1

:" But you would not do it like this! "
:" You would reshape 0c* to the desired length "
:" in a function and then iterate that function "
:" over a vector of numbers: "

{.p(x:^0c*)}'1+!5

Kotlin

fun main(args: Array<String>) {
    (1..5).forEach {
        (1..it).forEach { print('*') }
        println()
    }
}

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.

Lambdatalk

{def loops_for
 {lambda {:i :n}
  {if {>= :i :n}
   then (end of loop)
   else {br}{S.map {lambda {} *} {S.serie 0 :i}}
        {loops_for {+ :i 1} :n}}}}
-> loops_for

{loops_for 0 5}
-> 
* 
* * 
* * * 
* * * * 
* * * * * (end of loop)

a simpler way, using {S.map function {S.serie start end [step]}

{S.map {lambda {:i} {br} 
{S.map {lambda {:i} *} 
{S.serie 1 :i}}}
{S.serie 1 5}}
-> 
 * 
 * * 
 * * * 
 * * * * 
 * * * * *

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

langur

for i = 0; i < 5; i += 1 {
    for j = 0; j <= i; j += 1 {
        write "*"
    }
    writeln()
}

A for of loop iterates over keys (when used with an array, string, or hash) and a for in loop iterates over values.

for i of 5 {
    for of i {
        write "*"
    }
    writeln()
}

Or, with one for loop...

for i of 5 {
    writeln "*" * i
}

Lasso

loop(5) => {^
    loop(loop_count) => {^ '*' ^}
    '\r'
^}

LC3 Assembly

      .ORIG      0x3000

      AND        R1,R1,0
      ADD        R1,R1,1
      AND        R5,R5,0
      ADD        R5,R5,5
      NOT        R5,R5

LOOPI LD         R0,STAR
      AND        R2,R2,0
      ADD        R3,R1,0

LOOPJ OUT
      ADD        R2,R2,1
      NOT        R4,R2
      ADD        R4,R3,R4
      BRZP       LOOPJ

      LD         R0,LF
      OUT

      ADD        R1,R1,1
      ADD        R4,R1,R5
      BRN        LOOPI

      HALT

STAR  .FILL      0x2A
LF    .FILL      0x0A

      .END

Output:

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

LDPL

data:
i is number
j is number

procedure:
for i from 1 to 6 step 1 do
    for j from 0 to i step 1 do
        display "*"
    repeat
    display lf
repeat

Output:

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

LIL

In LIL for takes a before loop code block for init, a conditional expression (true to enter loop step, false to exit loop), an after each loop step code block for value reassignment, followed by the code for the loop.

for {set i 1} {$i <= 5} {inc i} {
    for {set j 1} {$j <= $i} {inc j} {
        write "*"
    }
    print
}

Output:

prompt$ lil loopsFor.lil
*
**
***
****
*****

The for statement in LIL, like Tcl, is pretty flexible and is not limited to simple incremented variable style loops.

Lingo

repeat with i = 1 to 5
  str = ""
  repeat with j = 1 to i
    put "*" after str
  end repeat
  put str
end repeat

Lisaac

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

LiveCode

put 0 into n
repeat for 5 times                                                                                                   
  add 1 to n
  repeat for n times
    put "*"
  end repeat
  put return
end repeat

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

single loop

for i = 1, 5 do
  print(string.rep("*", i))
end

or

for i = 1, 5 do
  print(("*"):rep(i))
end

M2000 Interpreter

By default there For loops always perform on execution of block. If end value is smaller than fist value, then step adjust to that direction. When first value is equal to second value then if we declare step negative end value after execution of block became start value minus absolute step, or if step is positive, became start value plus step. We can use a switch for interpreter to change IF's STEP to act as BASIC's, and sign of step always used, and there is situations where block can't executed.

For i=1 to 5
      For j=1 to i
            Print "*";
      Next j
      Print
Next i
Print "End1"
For i=1 to 5 {
      For j=1 to i {
            Print "*";
      }
      Print
}
Print "End2"

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 /Wolfram Language

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).

MiniScript

Literal interpretation of the task is somewhat complicated by the fact that the standard implementation of print in MiniScript adds a line break:

for i in range(1,5)
    s = ""
    for j in range(1, i)
        s = s + "*"
    end for
    print s
end for

Output:

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

However, it is worth noting that MiniScript's string replication operator (*) makes a more natural solution possible:

for i in range(1,5)
    print "*" * i
end for

(Output same as above.)

MIPS Assembly

Thanks to ChibiAliens for the header and footer as well as print routines.

.include "\SrcAll\Header.asm"
.include "\SrcAll\BasicMacros.asm"
.include "\SrcPSX\MemoryMap.asm"
.include "\SrcN64\MemoryMap.asm"
  
CursorX equ 0x100 
CursorY equ 0x101
  
main:
	li t3,5+1       ;outer loop counter
	li t2,1         ;inner loop counter
	move a2,t2      ;working copy of inner loop counter
loop:
	li a1,'*'
	jal PrintChar
	nop             ;needed on PlayStation after branches to prevent out-of-order execution.
	subiu a2,1     
	bnez a2,loop    
	nop
;overhead
	jal NewLine	;this doesn't use t2 so we don't care about out-of-order execution.
	addiu t2,1      ;increment outer loop counter
	move a2,t2      ;next time, we'll print one more * than we did last time.
	bne t2,t3,loop  ;are we done yet? If not, loop.
	nop
 
HALT:
	j HALT          ;halt the CPU - we're done
	nop

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
MyFont:
.ifdef buildn64				
	.incbin "\ResN64\ChibiAkumas.fnt"
.endif
.ifdef buildPSX				
	.incbin "\ResPSX\ChibiAkumas.fnt"
.endif

.include "\SrcALL\graphics.asm"
	
.include "..\\SrcAll\monitor.asm"  	
.include "\SrcN64\Footer.asm"

Output:

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

Screenshot of Nintendo 64 emulator

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

Morfa

import morfa.base;

for (i in 0..5) 
{
    for (j in 0..i+1) 
    {
        print("*");
    }
    println("");
}

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 !

Nanoquery

for ($i = 1) ($i <= 5) ($i = $i+1)
    for ($j = 0) ($j < $i) ($j = $j+1)
        print "*"
    end for
    println
end for

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"))

Nim

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

NS-HUBASIC

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

Nu

for i in 1..5 {
	for j in 1..$i {
		print -n "*"
	}
	print ""
}

Oberon-2

Works with oo2c Version 2

MODULE LoopFor;
IMPORT 
  Out;
VAR
  i, j: INTEGER;
 
BEGIN
  FOR i := 1 TO 5 DO
    FOR j := 1 TO i DO
      Out.Char('*');
    END;
    Out.Ln
  END
END LoopFor.

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

Odin

package main

import "core:fmt"

main :: proc() {
    for i := 1 ; i <= 5 ; i += 1 {
        for j := 1; j <= i; j += 1 {
    		fmt.printf("*")
        }
        fmt.println()
    }
}

Oforth

: loopFor(n)
| i j |
   n loop: i [
      i loop: j [ "*" print ]
      printcr ;

Onyx

1 1 5 {dup {`*'} repeat bdup bpop ncat `\n' cat print} for flush

Using repeat inside the for loop instead of nesting another for loop is shorter and more efficient.

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.

PascalABC.NET

##
for var i:=1 to 5 do
begin
  for var j:=1 to i do
    Write('*');
  Writeln
end;

Perl

for(my $x = 1; $x <= 5; $x++) {
  for(my $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;

or equivalently

map {print '*' x $_ . "\n"} 1..5;

Phix

for i=1 to 5 do
    for j=1 to i do
        puts(1,"*")
    end for
    puts(1,"\n")
end for

Phixmonti

/# Rosetta Code problem: https://rosettacode.org/wiki/Loops/For
by Galileo, 11/2022 #/

include ..\Utilitys.pmt

5 for
    for
        "*" print
    endfor
    nl
endfor

5 for '*' swap repeat ? endfor

Output:

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

=== Press any key to exit ===

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";
}

or

foreach (range(1, 5) as $i)
  echo str_repeat('*', $i) , PHP_EOL;

Picat

go =>
  N = 5,
  foreach(I in 1..N) 
    foreach(_J in 1..I) 
      print("*") 
    end, 
    nl 
  end.

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");
   }
}

PILOT

Core PILOT does not offer any way of printing without a newline, so in the inner loop we concatenate another star onto the string variable $stars each time round and then print it in the outer loop.

C  :i = 1
*OuterLoop
C  :j = 0
C  :$stars =
*InnerLoop
C  :j = j + 1
C  :$stars =*$stars
J ( j < i )          :*InnerLoop
T  :$stars
C  :i = i + 1
J ( i < 6 )          :*OuterLoop
END:

PL/I

Basic version:

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

Advanced version:

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

Due to the new line requirement a mono line version is not possible

put edit ((('*' do j = 1 to i)do i=1 to 5))(a);  /* no new line */

Plain English

Plain English doesn't allow the direct nesting of loops. Instead, you are encouraged to make one routine for each loop and let the routine headers describe what the loops are doing.

To run:
Start up.
Write a triangle of asterisks on the console given 5.
Wait for the escape key.
Shut down.

To write a row of asterisks on the console given a number:
If a counter is past the number, write "" on the console; exit.
Write "*" on the console without advancing.
Repeat.

To write a triangle of asterisks on the console given a size:
If a counter is past the size, exit.
Write a row of asterisks on the console given the counter.
Repeat.

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 "*" * $_.

Processing

size( 105,120 );

for ( int i=20; i<=100; i+=20 )
   for ( int j=10; j<=i; j+=20 )
      text( "*", j,i );

Prolog

Prolog has a built in iterator, between(Lo,Hi,I) which binds the value of I to successive values from Lo to Hi. This is the closest thing Prolog has to a 'for' loop.

example :- 
    between(1,5,I), nl, between(1,I,_J),
    write('*'), fail.
example.

?- example.

*
**
***
****
*****
true.

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

or

print('\n'.join('*' * i for i in range(1, 6)))

QB64

CBTJD: 2020/03/14

FOR c = 1 TO 5
    FOR n = 1 TO c
        PRINT "*";
    NEXT
    PRINT
NEXT

Quackery

5 times [ i^ 1+ times [ say "*" ] cr ]

Output:

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

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))

Raku

(formerly 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;

Rapira

for N from 1 to 5 do
  output: "*" * N
od

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 ""
]

Red

Red[]

repeat i 5 [
    loop i [prin "*"]
    prin newline
]

ReScript

let s = ref("")
for i in 1 to 5 {
  for _ in 1 to i {
    s := Js.String2.concat(s.contents, "*")
  }
  s := Js.String2.concat(s.contents, "\n")
}
Js.log(s.contents)

Output:

bsc for.res > for.js
node for.js
*
**
***
****
*****

Retro

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

REXX

using concatenation

/*REXX program demonstrates an outer DO loop controlling the inner DO loop with a "FOR".*/

       do j=1  for 5                             /*this is the same as:   do j=1  to 5  */
       $=                                        /*initialize the value to a null string*/
              do k=1  for j                      /*only loop for a   J   number of times*/
              $= $ || '*'                        /*using concatenation  (||)  for build.*/
              end   /*k*/
       say $                                     /*display character string being built.*/
       end          /*j*/                        /*stick a fork in it,  we're all done. */

output:

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

using abutment

/*REXX program demonstrates an outer DO loop controlling the inner DO loop with a "FOR".*/

       do j=1  for 5                             /*this is the same as:   do j=1  to 5  */
       $=                                        /*initialize the value to a null string*/
              do k=1  for j                      /*only loop for a   J   number of times*/
              $= $'*'                            /*using abutment for the construction. */
              end   /*k*/
       say $                                     /*display character string being built.*/
       end          /*j*/                        /*stick a fork in it,  we're all done. */

output is identical to the 1^st REXX version.

Ring

can be done in just one line:

for i = 1 to 5 for x = 1 to i see "*" next see nl next

or multiple line

for i = 1 to 5
     for x = 1 to i
         see "*" 
     next
     see nl 
next

RPL

RPL provides two types of counting loops: FOR..NEXT and START..NEXT, the latter looping without providing access to its counter.

≪ 1 5 FOR j
     ""
     1 j START
        "*" +
     NEXT
  NEXT
≫
'LOOPS' STO

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	Range#each
for i in 1..5 for j in 1..i print "*" end puts end	(1..5).each do \|i\| (1..i).each do \|j\| 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 }

Rust

The compiler warns when you create an unused variable; here we use _ to avoid this effect.

fn main() {
    for i in 0..5 {
        for _ in 0..=i {
            print!("*");
        }

        println!();
    }
}

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;

/* Possible without the inner loop. Notice TRIM is replaced with STRIP,
otherwise there is a blank space on the left */

data _null_;
length a $5;
do n=1 to 5;
  a=strip(a) !! "*";
  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;

Scala

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

Scheme

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

Scilab

Works with: Scilab version 5.5.1

for i=1:5
    s=""
    for j=1:i
        s=s+"*"
    end
    printf("%s\n",s)
end

Output:

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

Seed7

$ include "seed7_05.s7i";

const proc: main is func
  local
    var integer: I is 1;
    var integer: J is 1;	  

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

Output:

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

SETL

for i in {1..5} loop
    for j in {1..i} loop
        nprint( '*' );
    end loop;
    print;    -- new line
end loop;

Sidef

for(;;) loop:

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

for([]) loop:

for (1..5) { |i|
    for (1..i) { print '*' }
    print "\n"
}

for-in loop:

for i in (1..5) {
    for j in (1..i) { print '*' }
    print "\n"
}

Idiomatic:

5.times { |i|
    i.times { print '*' }
    print "\n"
}

Simula

Works with: SIMULA-67

begin
   integer i,j;
   for i:=1 step 1 until 5 do 
   begin 
      for j:=1 step 1 until i do 
         outtext("*");
      outimage
   end
end

Slate

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

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

SNUSP

       / \         
         <
       < < 
       < /<<<<<.\
       . ?    
       > \->>>>>/
       > !
       > > 
       ! > 
    />-\ />+>+\  
       ? ?  
    \+</ \ -<</ 
       < !
       < +                                                                 
       - >
  /   !\?/#     
  \+++++>+++++++++++++>\                                                                         
/++++++++++++++++++++++/                     
\++++++++++++++++++++\
                    $/

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

Sparkling

for (var row = 1; row <= 5; row++) {
    for (var col = 1; col <= row; col++) {
        printf("*");
    }

    print();
}

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

  repeat n from 1 to 5
    repeat m from 1 to n
      ser.tx("*")
    ser.str(string(13,10))

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

Output:

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

SPL

> i, 1..5
  > j, 1..i
    #.output("*",#.rs)
  <
  #.output()
<

Stata

forvalues n=1/5 {
	local s ""
	forvalues i=1/`n' {
		local s `s'*
	}
	display "`s'"
}

Mata

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

Suneido

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

Swift

for i in 1...5 {
    for _ in 1...i {
        print("*", terminator: "")
    }
    print()
}

Output:

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

Tailspin

Tailspin uses streams of values within streams of values rather than loops.

1..5 -> '$:1..$ -> '*';
' -> !OUT::write

Output:

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

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-83 BASIC

For loops in TI-83 BASIC take at least 3 arguments, with an optional fourth: For(variable,start,end[,step]. Parentheses don't need to be closed in TI-BASIC.

ClrHome
For(I,1,5
For(J,1,I
Output(I,J,"*
End
End

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);
    }
}

TransFORTH

: PRINTSTARS ( ROWS -- )
1 + 1 DO
I 0 DO
PRINT " * " LOOP
CR LOOP ;
5 PRINTSTARS

TUSCRIPT

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

Output:

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

TypeScript

for (let i: number = 0; i < 5; ++i) {
    let line: string = ""
    for(let j: number = 0; j <= i; ++j) {
        line += "*"
    }
    console.log(line)
}

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

ksh

Works with: ksh93

for ((x = 1; x <= 5; x += 1))
do
	for ((y = 0; y < x; y += 1))
	do
		print -n '*'
	done
	print
done

UnixPipes

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

Ursa

#
# for loop
#

decl int i j
for (set i 0) (< i 5) (inc i)
        for (set j 0) (< j (int (+ i 1))) (inc j)
                out "*" console
        end for
        out endl console
end for

Vala

int main (string[] args) {
    for (var i = 1; i <= 5; i++) {
        for (var j = 1; j <= i; j++) {
	    stdout.putc ('*');
        }
        stdout.putc ('\n');
    }
    return 0;
}

VBA

Option Explicit
Sub LoopEx()
    Dim i As Long, j As Long, s As String
    For i = 1 To 5
        s = ""
        For j = 1 To i
            s = s + "*"
        Next
        Debug.Print s
    Next
End Sub

VBScript

Option Explicit
Dim i, j, s
For i = 1 To 5
    s = ""
    For j = 1 To i
        s = s + "*"
    Next
    WScript.Echo s
Next

Vedit macro language

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

Verilog

module main;
  integer  i, j;
  
  initial begin

    for(i = 1; i <= 5; i = i + 1) begin
    	for(j = 1; j <= i; j = j + 1) $write("*");
    	$display("");
    end
  $finish ;
  end
endmodule

Vim Script

The two-loop approach determined in the description is solved in a similar manner to Python (initial solution) and Nim, using the inbuilt function, range(), which technically may be considered a for each loop. Nonetheless, it is an incrementing integer solution like many others provided. The script will append the output to the end of the current buffer. It uses inbuilt functions append(), line(), setline(), and getline():

for i in range(1, 5)
  call append(line('$'), '')
  for j in range(1, i)
    call setline(line('$'), getline('$') .. '*')
  endfor
endfor

If the constraint to use two for loops was absent, the more concise Vim Script solution ― similar to idiomatic Python solution #2 ― would be (this time using builtin functions echoc[onsole] and repeat() to demonstrate another approach to generating the output, i.e., to the console):

for i in range(1, 5)
  echoc repeat('*', i)
endfor

V (Vlang)

fn main() {
    for i in 1..6 {
        for _ in 1..i+1 {
            print("*")
        }
        print("\n")
    }
}

Output:

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

Wart

for i 1 (i <= 5) ++i
  for j 0 (j < i) ++j
    pr "*"
  (prn)

Wee Basic

print 1 "" ensures the end of program text is separate from the asterisk characters.

for y=0 to 4
print 1 ""
for x=0 to y
print 1 at x,y "*"
next
next
end

Wren

for (i in 1..5) {
    for (j in 1..i) System.write("*")
    System.print()
}

Output:

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

x86 Assembly

This subroutine uses only the original 16-bit 8086 instruction set; it is written for DOS, but could be adapted to run under other operating systems.

loops:      mov       bx,      1    ; outer loop counter

outerloop:  mov       cx,      bx   ; inner loop counter
            mov       dl,      42   ; '*' character

innerloop:  mov       ah,      6
            int       21h           ; print

            dec       cx
            jcxz      innerdone
            jmp       innerloop

innerdone:  mov       dl,      10   ; newline
            mov       ah,      6
            int       21h

            inc       bx
            cmp       bx,      6
            jne       outerloop

            ret

XBasic

Works with: Windows XBasic

PROGRAM "for"

DECLARE FUNCTION Entry()

FUNCTION Entry()
  FOR i% = 1 TO 5
    FOR j% = 1 TO i%
      PRINT "*";
    NEXT j%
    PRINT
  NEXT i%
END FUNCTION
END PROGRAM

XBS

const repChar:string = "*";
const maxIters = 5;
for(i=1;maxIters;1){
	set str:string = "";
	for(o=1;i;1){
		str+=repChar;
	}
	log(str);
}

Output:

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

XLISP

The equivalent of other languages' FOR or DO loops can be written using DO:

(DO ((I 1 (+ I 1))) ((> I 5))
    (DO ((J 0 (+ J 1))) ((= J I))
        (DISPLAY "*"))
    (NEWLINE))

Output:

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

This construct is not, however, very idiomatic: loops in XLISP are mostly written using recursion.

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);
    ]

Z80 Assembly

For the Amstrad CPC (should work with e.g. the built-in assembler in JavaCPC; use call &4000 to start from BASIC):

org &4000		; put code at memory address 0x4000
wr_char equ &bb5a ; write ASCII character in register A to screen
				; (jumps into CPC ROM)

; put registers on stack so we can return to BASIC later
push bc
push de
push hl

ld b,5		; loop from 5 to 1

row:

push bc	; save outer loop variable

; calculate inner loop limit (6 - outer loop variable)
ld a,6
sub b
ld b,a

column:

ld a,42	; asterisk in ASCII
call wr_char
djnz column ; decrement B, jump to label if non-zero

pop bc	; restore outer loop

; print carriage return/line feed
ld a,13
call wr_char
ld a,10
call wr_char

djnz row

; restore registers
pop hl
pop de
pop bc
ret	; return to BASIC interpreter

Zig

const std = @import("std");

pub fn main() !void {
    const stdout_wr = std.io.getStdOut().writer();
    for (1..6) |n| {
        for (0..n) |_| {
            try stdout_wr.writeAll("*");
        }
        try stdout_wr.writeAll("\n");
    }
}

Output:

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

zkl

foreach i in ([1..5]){
   foreach j in (i){print("*")}
   println();
}

Output:

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