Convert Hexadecimal String to Integer Without strtol or sscanf functions

Code

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

uint16_t hex_to_uint(const char *str) {
    uint16_t num = 0;
    while (*str)
    {
        num *= 16;
        if (*str >= '0' && *str <= '9')
            num += *str - '0';
        if (*str >= 'A' && *str <= 'F')
            num += *str - 'A' + 10;
        if (*str >= 'a' && *str <= 'f')
            num += *str - 'a' + 10;
        //printf("%d\n", num);
        str++;
    }
    return num;
}

int main() {
    char hex[10];
    scanf("%s", hex);

    printf("%u", hex_to_uint(hex));
    return 0;
}

Solving Approach