119. 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;
    uint8_t nibble;

    while (*str != '\0') {
        if (*str >= '0' && *str <= '9')
            nibble = *str - '0';
        else if (*str >= 'A' && *str <= 'F')
            nibble = (*str - 'A') + 10;
        else if (*str >= 'a' && *str <= 'f')
            nibble = (*str - 'a') + 10;
        else
            return 0; // or handle error

        val = (val << 4) | nibble;
        str++;
    }

    return val;
}

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

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