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;
    uint16_t digit;
    for(int i=0;str[i];i++){
        if(str[i]>='0' && str[i]<='9')
            digit = str[i] - '0';
        else if((str[i]>='A' && str[i]<='F'))
            digit = str[i] - 'A' + 10;
        else if((str[i]>='a' && str[i]<='f'))
            digit = str[i] - 'a' + 10;
        else
            return -1;
        result = (result << 4) | digit;
    }
    return result;
}

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

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

Solving Approach