Convert Hexadecimal String to Integer Without strtol or sscanf functions

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

uint16_t hex_to_uint(const char *str) {
    // Your logic here
    uint16_t val = 0;
    for (int i = 0 ; str[i] != '\0' ; i++)
    {
        int digit = 0;
        if (str[i] >= '0' && str[i] <= '9')
        {
            digit = str[i] - '0';
            
        }
        else if (str[i] >= 'A' && str[i] <= 'F')
        {
            digit = str[i] - 'A' + 10; 
        }
        else if (str[i] >= 'a' && str[i] <= 'f')
        {
            digit = str[i] - 'a' + 10; 
        }


        val = (val << 4) | digit;

    }
    return val;
}

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

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