Convert Hexadecimal String to Integer Without strtol or sscanf functions

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

uint16_t hex_to_uint(const char *str) {
    uint16_t val = 0;
    for (int i = 0; str[i]; i++) {
        char c = str[i];
        int digit;

        if (c >= '0' && c <= '9') {
            digit = c - '0';
        } else if (c >= 'A' && c <= 'F') {
            digit = c - 'A' + 10;
        } else if (c >= 'a' && c <= 'f') {
            digit = c - 'a' + 10;
        } else {
            // Invalid character, stop or handle error
            break;
        }

        val = (val << 4) | digit;
    }
    return val;
}


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

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