Reversing all the bits in an integer

main.c

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

int main(int argc, char* argv[]) {
    int a = 13;
    printf("%d\n", a);
    long long i;
    for (i = 0; i < sizeof(int); i++) {
        printf("%02hhx ", ((unsigned char*)&a)[i]);
    }
    
    int reversed = 0;
    for (i = 0; i < 32; i++) {
        reversed |= ((a >> i) & 1) << (32 - i - 1);
    }
    
    printf("\n%d\n", reversed);
 
    for (i = 0; i < sizeof(int); i++) {
        printf("%02hhx ", ((unsigned char*)&a)[i]);
    }
    return 0;
}