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) {
    // Your logic here
    uint16_t result = 0;
    int i = 0;
    int val;
    while(str[i]!= '\0'){
        if(str[i] >= '0' & str[i] <= '9'){
            val = str[i] - '0';
        }
        else if(str[i] >= 'A' & str[i] <= 'Z'){
            val = str[i] -'A'+10;
        }
        else if(str[i] >= 'a' & str[i] <= 'z'){
            val = str[i] -'a'+10;
        }
        else {
            break;
        }
        result = (result << 4) | val;
        i++;
    }
    return result;
}

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

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

Solving Approach