Adam Pierce Adam Pierce - 1 year ago 227
C Question

Where is the itoa function in Linux?

is a really handy function to convert a number to a string. Linux does not seem to have
, is there an equivalent function or do I have to use
sprintf(str, "%d", num)

Answer Source

EDIT: Sorry, I should have remembered that this machine is decidedly non-standard, having plugged in various non-standard libc implementations for academic purposes ;-)

As itoa() is indeed non-standard, as mentioned by several helpful commenters, it is best to use sprintf(target_string,"%d",source_int) or (better yet, because it's safe from buffer overflows) snprintf(target_string, size_of_target_string_in_bytes, "%d", source_int). I know it's not quite as concise or cool as itoa(), but at least you can Write Once, Run Everywhere (tm) ;-)

Here's the old (edited) answer

You are correct in stating that the default gcc libc does not include itoa(), like several other platforms, due to it not technically being a part of the standard. See here for a little more info. Note that you have to

#include <stdlib.h>

Of course you already know this, because you wanted to use itoa() on Linux after presumably using it on another platform, but... the code (stolen from the link above) would look like:


/* itoa example */
#include <stdio.h>
#include <stdlib.h>

int main ()
  int i;
  char buffer [33];
  printf ("Enter a number: ");
  scanf ("%d",&i);
  itoa (i,buffer,10);
  printf ("decimal: %s\n",buffer);
  itoa (i,buffer,16);
  printf ("hexadecimal: %s\n",buffer);
  itoa (i,buffer,2);
  printf ("binary: %s\n",buffer);
  return 0;


Enter a number: 1750
decimal: 1750
hexadecimal: 6d6
binary: 11011010110

Hope this helps!

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