inttobin

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

char *itoa(unsigned int val, int base)
{
    static char buf[32] = {0};
    int i = 32;

    for(; val && i; --i, val /= base)
        buf[i] = "0123456789abcdef"[val % base];

    return &buf[i+1];
}

int main (void)
{
    int n;

    printf("Enter  a value: ");
    scanf("%d", &n);
    printf("%d -> hex %s\n", n, itoa(n, 16));
    printf("%d -> oct %s\n", n, itoa(n, 8));
    printf("%d -> bin %s\n", n, itoa(n, 2));
    system("pause > nul");
    return 0;
}