Loop/For

From Rosetta Code

Specifically print out the following pattern by using one for loop nested in another:

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

Contents 1 Ada 2 BASIC 3 C 4 ColdFusion 5 Common Lisp 6 D 7 Forth 8 Fortran 9 Haskell 10 J 11 Java 12 JavaScript 13 Logo 14 MAXScript 15 OCaml 16 Pascal 17 Perl 18 Pop11 19 Python 20 Ruby 21 Scheme 22 UnixPipes

[edit] Ada

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

[edit] BASIC

Works with: QuickBasic version 4.5

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

[edit] C

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

[edit] 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>

[edit] Common Lisp

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

[edit] D

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

Foreach Range Statement since D2.003

foreach(i ; 0..5) {
  foreach(j ; 0..i+1)
    writef("*") ;
  writefln() ;
}

[edit] Forth

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

[edit] Fortran

Works with: Fortran version 90 and later

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

[edit] Haskell

import Control.Monad

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

[edit] J

J is array-oriented, so there is very little need for loops. For example, 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 never see J code like this.

[edit] Java

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

[edit] JavaScript

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

[edit] Logo

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

[edit] MAXScript

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

[edit] OCaml

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

[edit] 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.
 

[edit] Perl

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

[edit] Pop11

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

[edit] 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
 

[edit] Ruby

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

[edit] Scheme

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

[edit] UnixPipes

yes \ | cat -n | while read n ; do
  yes \* | head -n $n | xargs -n $n echo
done