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;
    while(*str != '\0'){
        char c = *str;
        if(c >= 97 && c<= 122){
            c = c - 32;
        }
        int digit = ( c >= 'A') ? (c - 'A' + 10) : ( c - '0');
        val = (val << 4) | digit;
        str++;
    }
    return val;
}

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

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