120. Convert Integer to Hex String Without sprintf or itoa functions

#include <stdio.h>
#include <stdint.h>

void print_hex(uint16_t num) {
    char str[6];
    int i;
    char tmp;
    char *literals = "0123456789ABCDEF";

    if(!num)
    {
        str[0] = '0';
        str[1] = '\0';
        printf("%s", str);
        return;
    }

    i = 0;
    while(num)
    {
        str[i++] = literals[num % 16];
        num /= 16;
    }
    str[i] = '\0';
    int j = 0;

    while(j < i)
    {
        tmp = str[--i];
        str[i] = str[j];
        str[j++] = tmp;
    }
    printf("%s", str);
}

int main() {
    uint16_t num;
    scanf("%hu", &num);
    print_hex(num);
    return 0;
}