Repeat a string
You are encouraged to solve this task according to the task description, using any language you may know.
Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha"
If there is a simpler/more efficient way to repeat a single “character”, you might want to show that as well (i.e. repeat-char("*", 5) => "*****").
Ada
In Ada multiplication of an universal integer to string gives the desired result. Here is an example of use: <lang Ada>with Ada.Strings.Fixed; use Ada.Strings.Fixed; with Ada.Text_IO; use Ada.Text_IO;
procedure String_Multiplication is begin
Put_Line (5 * "ha");
end String_Multiplication;</lang> Sample output:
hahahahaha
ALGOL 68
<lang algol68>print (5 * "ha") </lang>
C
<lang c>#include <stdio.h>
- include <stdlib.h>
- include <string.h>
char * string_repeat( int n, const char * s ) {
size_t slen = strlen(s); char * dest = (char *)calloc(n*slen+1, sizeof(char));
int i; char * p;
for ( i=0, p = dest; i < n; ++i, p += slen ) {
memcpy(p, s, slen);
}
return dest;
}
int main() {
printf("%s\n", string_repeat(5, "ha"));
return 0;
}</lang>
To repeat a single character <lang c>#include <stdio.h>
- include <stdlib.h>
- include <string.h>
char * char_repeat( int n, char c ) {
char * dest = (char *)calloc(n+1, sizeof(char)); memset(dest, c, n); return dest;
}
int main() {
printf("%s\n", char_repeat(5, '*'));
return 0;
}</lang>
C++
<lang cpp>#include <string>
- include <iostream>
std::string repeat( const std::string &word, int times ) {
std::string result ;
result.reserve(times*word.length()); // avoid repeated reallocation
for ( int a = 0 ; a < times ; a++ )
result += word ;
return result ;
}
int main( ) {
std::cout << repeat( "Ha" , 5 ) << std::endl ; return 0 ;
}</lang>
To repeat a single character: <lang cpp>#include <string>
- include <iostream>
int main( ) {
std::cout << std::string( 5, '*' ) << std::endl ; return 0 ;
}</lang>
C#
<lang csharp> String s = "".PadLeft(5, 'X').Replace("X", "ha")</lang>
To repeat a single character: <lang csharp> String s = "".PadLeft(5, '*')</lang>
Clojure
<lang lisp>(apply str (repeat 5 "ha"))</lang>
Common Lisp
<lang lisp>(defun repeat-string (n string)
(with-output-to-string (stream) (loop repeat n do (write-string string stream))))
(princ (repeat-string 5 "hi"))</lang>
A single character may be repeated using just the builtin make-string:
<lang lisp>(make-string 5 :initial-element #\X)</lang>
produces “XXXXX”.
D
Repeating a string: <lang d>import std.stdio; import std.string;
void main() {
writefln(repeat("ha", 5));
}</lang> Repeating a character with vector operations: <lang d>import std.stdio;
void main() {
char[]str; // create the dynamic array str.length = 5; // set the length str[]='*'; // set all characters in the string to '*' writefln(str);
}</lang>
E
<lang e>"ha" * 5</lang>
Factor
<lang factor>: repeat-string ( str n -- str' ) swap <repetition> concat ;
"ha" 5 repeat-string print</lang>
Forth
<lang forth>: place-n { src len dest n -- }
0 dest c! n 0 ?do src len dest +place loop ;
create test 256 allot s" ha" test 5 place-n test count type \ hahahahaha
test 10 char * fill \ repeat a single character test 10 type </lang>
Fortran
<lang fortran>program test_repeat
write (*, '(a)') repeat ('ha', 5)
end program test_repeat</lang> Output:
hahahahaha
Haskell
For a string of finite length:
<lang haskell>concat $ replicate 5 "ha"</lang>
For an infinitely long string:
<lang haskell>cycle "ha"</lang>
To repeat a single character:
<lang haskell>replicate 5 '*'</lang>
J
<lang j> 5 # '*' NB. repeat each item 5 times
5 # 'ha' NB. repeat each item 5 times
hhhhhaaaaa
(5 * # 'ha') $ 'ha' NB. repeat array 5 times (explicit)
hahahahaha
5 ((* #) $ ]) 'ha' NB. repeat array 5 times (tacit)
hahahahaha</lang>
Java
There's no function or operator to do this in Java, so you have to do it yourself. <lang java5>public static String repeat(String str, int times){
StringBuilder ret = new StringBuilder(); for(int i = 0;i < times;i++) ret.append(str); return ret.toString();
}
public static void main(String[] args){
System.out.println(repeat("ha", 5));
}</lang>
Or even shorter: <lang java5>public static String repeat(String str, int times){
return new String(new char[times]).replace("\0", str);
}</lang>
JavaScript
This solution creates an array of n+1 null elements, then joins them using the target string as the delimiter <lang javascript>String.prototype.repeat = function(n) {
return new Array(1 + parseInt(n, 10)).join(this);
}
alert("ha".repeat(5)); // hahahahaha</lang>
Logo
<lang logo>to copies :n :thing [:acc "||]
if :n = 0 [output :acc] output (copies :n-1 :thing combine :acc :thing)
end</lang> or using cascade: <lang logo>show cascade 5 [combine "ha ?] "|| ; hahahahaha</lang>
OCaml
<lang ocaml>let string_repeat s n =
let len = String.length s in let res = String.create(n * len) in for i = 0 to pred n do String.blit s 0 res (i * len) len; done; (res)
- </lang>
testing in the toplevel: <lang ocaml># string_repeat "Hiuoa" 3 ;; - : string = "HiuoaHiuoaHiuoa"</lang>
Alternately: <lang ocaml>let string_repeat s n =
String.concat "" (Array.to_list (Array.make n s))
- </lang>
Or: <lang ocaml>let string_repeat s n =
Array.fold_left (^) "" (Array.make n s)
- </lang>
To repeat a single character: <lang ocaml>String.make 5 '*'</lang>
Oz
We have to write a function for this: <lang oz>declare
fun {Repeat Xs N}
if N > 0 then
{Append Xs {Repeat Xs N-1}}
else
nil
end
end
in
{System.showInfo {Repeat "Ha" 5}}</lang>
Perl
<lang perl>"ha" x 5</lang>
Perl 6
<lang perl6>"ha" x 5</lang>
(Note that the x operator isn't quite the same as in Perl 5: it now only creates strings. To create lists, use xx.)
PHP
<lang php>str_repeat("ha", 5)</lang>
PostScript
<lang PostScript>% the comments show the stack content after the line was executed % where rcount is the repeat count, "o" is for orignal, % "f" is for final, and iter is the for loop variable % % usage: rcount ostring times -> fstring
/times {
dup length dup % rcount ostring olength olength
4 3 roll % ostring olength olength rcount
mul dup string % ostring olength flength fstring
4 1 roll % fstring ostring olength flength
1 sub 0 3 1 roll % fstring ostring 0 olength flength_minus_one
{ % fstring ostring iter
1 index 3 index % fstring ostring iter ostring fstring
3 1 roll % fstring ostring fstring iter ostring
putinterval % fstring ostring
} for
pop % fstring
} def</lang>
PowerBASIC
<lang powerbasic>MSGBOX REPEAT$(5, "ha")</lang>
Pure
str_repeat is defined by pattern-matching: repeating any string 0 times results in the empty string; while repeating it more than 0 times results in the concatenation of the string and (n-1) further repeats.
<lang pure>> str_repeat 0 s = ""; > str_repeat n s = s + (str_repeat (n-1) s) if n>0; > str_repeat 5 "ha"; "hahahahaha" ></lang>
Python
<lang python>"ha" * 5 # ==> "hahahahaha"</lang>
PowerShell
<lang powershell>"ha" * 5 # ==> "hahahahaha"</lang>
R
<lang ruby>paste(rep("ha",5), collapse=)</lang>
Ruby
<lang ruby>"ha" * 5 # ==> "hahahahaha"</lang>
Scala
<lang scala>"ha" * 5 // ==> "hahahahaha"</lang>
Scheme
<lang scheme>(define (string-repeat n str) (fold string-append "" (make-list n str))) (string-repeat 5 "ha") ==> "hahahahaha"</lang>
To repeat a single character: <lang scheme>(string-make 5 #\*)</lang>
Tcl
<lang tcl>string repeat "ha" 5 ;# => hahahahaha</lang>
Ursala
<lang Ursala>#import nat
repeat = ^|DlSL/~& iota
- cast %s
example = repeat('ha',5)</lang> output:
'hahahahaha'