How to convert an integer to a character array using C

Make use of the log10 function to determine the number of digits and do like below:

char * toArray(int number)
{
    int n = log10(number) + 1;
    int i;
    char *numberArray = calloc(n, sizeof(char));
    for (i = n-1; i >= 0; --i, number /= 10)
    {
        numberArray[i] = (number % 10) + '0';
    }
    return numberArray;
}

Or the other option is sprintf(yourCharArray,"%ld", intNumber);


'sprintf' will work fine, if your first argument is a pointer to a character (a pointer to a character is an array in 'c'), you'll have to make sure you have enough space for all the digits and a terminating '\0'. For example, If an integer uses 32 bits, it has up to 10 decimal digits. So your code should look like:

int i;
char s[11]; 
...
sprintf(s,"%ld", i);

Use itoa, as is shown here.

char buf[5];
// Convert 123 to string [buf]
itoa(123, buf, 10);

buf will be a string array as you documented. You might need to increase the size of the buffer.


The easy way is by using sprintf. I know others have suggested itoa, but a) it isn't part of the standard library, and b) sprintf gives you formatting options that itoa doesn't.

Tags:

C