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 result = 0;
    
    while(*str != '\0'){
        uint16_t hex = 0;
        if (*str >= 'a'){
            hex = (*str - 'a') + 10;
        }
        else if (*str >= 'A'){
            hex = (*str - 'A') + 10;
        }
        else {
            hex = (*str - '0');
        }
        result = (result * 16) + hex;
        str++;

    }
    return result;
}

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

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

Solving Approach