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 result = 0;
     for (int i = 0; str[i] != '\0'; i++) {
        char c = str[i];
        uint8_t value;
        
        if (c >= '0' && c <= '9') {
            value = c - '0';
        }
        else if (c >= 'A' && c <= 'F') {
            value = c - 'A' + 10;
        }
        else if (c >= 'a' && c <= 'f') {
            value = c - 'a' + 10;
        }
        else {
            // Invalid character - return 0
            return 0;
        }
        
        // Shift left by 4 bits (multiply by 16) and add new value
        result = (result << 4) | value;
    }
    return result;
}

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

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