Convert Integer to Hex String Without sprintf or itoa functions

Code

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

void print_hex(uint16_t num) {
    // Your logic here
    char lookup[] = "0123456789ABCDEF";
    char str[5];
    int i = 0;
    if(num == 0){printf("0");}
    while(num != '\0'){
        str[i++] = lookup[num&0xf];
        num >>= 4;
    }
    for(i = i-1;i>=0;i--){
        printf("%c",str[i]);
    }
}

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

Solving Approach