Converting an integer to binary in C

Question

I\'m trying to convert an integer 10 into the binary number 1010.

This code attempts it, but I get a segfault on the strcat():

int int_to_bin(int k)
{
          


        

Answer 1

Well, I had the same trouble ... so I found this thread

I think the answer from user:"pmg" does not work always.

unsigned int int_to_int(unsigned int k) {
    return (k == 0 || k == 1 ? k : ((k % 2) + 10 * int_to_int(k / 2)));
}

Reason: the binary representation is stored as an integer. That is quite limited. Imagine converting a decimal to binary:

 dec 255  -> hex 0xFF  -> bin 0b1111_1111
 dec 1023 -> hex 0x3FF -> bin 0b11_1111_1111

and you have to store this binary representation as it were a decimal number.

I think the solution from Andy Finkenstadt is the closest to what you need

unsigned int_to_int(unsigned int k) {
    char buffer[65]; // any number higher than sizeof(unsigned int)*bits_per_byte(8)
    return itoa( atoi(k, buffer, 2) );
}

but still this does not work for large numbers. No suprise, since you probably don't really need to convert the string back to decimal. It makes less sense. If you need a binary number usually you need for a text somewhere, so leave it in string format.

simply use itoa()

char buffer[65];
itoa(k, buffer, 2);