hex_dec.c

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

#define BITMASK(n) (1 << (n))

void divide_and_print(int x){

    printf("Dec: %d\n", x);
    printf("Hex: 0x%X\n", x);
    printf("Bin: ");

    int found_first_one = 0;
    int i = 31;

    for(i = 31; i >= 0; i--){
        if(x&BITMASK(i)){
            printf("1");
            if(found_first_one == 0){
                found_first_one = 1;
            }
        }
        else if(found_first_one){
            printf("0");
        }
    }

    printf("\n");
}

int main(int argc, char *argv[]){

    if(argc != 2){
        printf("[Usage]: Input a valid Dec number\n");
        return -1;
    }

    int x = atoi(argv[1]);
    divide_and_print(x);

    return 0;
}