Convert Binary String to Integer Without strtol function or Libraries

Code

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

uint16_t binary_to_uint(const char *str) {
    // Your logic here
    int i = 0;
    int length = 0;
    while (str[length] != '\0') ++length;
    length = length - 1;
    uint16_t res = 0;
    while (str[i] != '\0'){
        uint16_t val = 1;
            if (str[i] == '1'){
                for (int j = length; j > 0; j--){
                val = val * 2;
                }
            } else val = 0;
           
        res += val;
        ++i;
        --length;
    }
    return res;
}

int main() {
    char bin[20];
    scanf("%s", bin);

    printf("%u", binary_to_uint(bin));
    return 0;
}

Solving Approach