How to convert integer to string in C?

c string integer type-conversion
janko-m picture janko-m · Mar 11, 2012 · Viewed 1M times · Source

I tried this example:

/* 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;
}

but the example there doesn't work (it says the function itoa doesn't exist).

Answer

qwertz picture qwertz · Mar 11, 2012

Use sprintf():

int someInt = 368;
char str[12];
sprintf(str, "%d", someInt);

All numbers that are representable by int will fit in a 12-char-array without overflow, unless your compiler is somehow using more than 32-bits for int. When using numbers with greater bitsize, e.g. long with most 64-bit compilers, you need to increase the array size—at least 21 characters for 64-bit types.

Related questions

How to convert an int to string in C?

How do you convert an int (integer) to a string? I'm trying to make a function that converts the data of a struct into a string to save it in a file.

Read More
How do I concatenate const/literal strings in C?

I'm working in C, and I have to concatenate a few things. Right now I have this: message = strcat("TEXT ", var); message2 = strcat(strcat("TEXT ", foo), strcat(" TEXT ", bar)); Now if you have experience in C I'm sure you realize …

Read More
How do I create an array of strings in C?

I am trying to create an array of strings in C. If I use this code: char (*a[2])[14]; a[0]="blah"; a[1]="hmm"; gcc gives me "warning: assignment from incompatible pointer type". What is the correct way to do this? edit: …

Read More