Convert Hexadecimal String to Integer Without strtol or sscanf functions

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

uint16_t hex_to_uint(const char *str) {
    int result = 0;
    int hex_value = 0;
    for(int i=0; str[i] != '\0'; i++){
        if(str[i] >= '0' && str[i] <='9'){
            hex_value = str[i] - '0';
        }else if(str[i] >= 'a' && str[i] <= 'f'){
            hex_value = str[i] - 'a' + 10;
        }else if(str[i] >= 'A' && str[i] <= 'F'){
            hex_value = str[i] - 'A' + 10;
        }
        result = (result << 4) | hex_value;
    }
    return result;
}

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

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