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

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

char oct_to_hex(uint8_t n) {
    if (n<10) {
        return n + '0';
    }
    else if (n < 16) {
        return n - 10 + 'A';
    }
}

void print_hex(uint16_t num) {
    if (!num) {
        printf("0");
        return;
    }
    
    char hex_str[5] = {0};
    char *str = hex_str;
    while (num) {
        *str = oct_to_hex(num % 16);
        num /= 16;
        ++str;
    }

    for(int i = str - hex_str - 1; i >= 0; --i) {
        printf("%c", hex_str[i]);
    }

}

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