C function to convert an integer to a binary string

ToBinary.c

#include <stdio.h>
#include <stdlib.h>

char * toBinary(int n)
{
    const int size = sizeof(n) * 8;
    char * str = (char*)malloc(sizeof(char) * (size + 1));

    if (str)
    {
        for (int i = size - 1; i >= 0; i--)
        {
            str[i] = n % 2 + '0';
            n /= 2;
        }

        str[size] = '\0';
    }

    return str;
}

int main()
{
    int x = 16;
    char * s = toBinary(x);
    printf(s);
}