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) {
    int i = 0;
    int len = 0;
    uint16_t result = 0;
    int factor=1;

    while (str[i] != '\0') {
        len++;
        i++;
    }

    for (int j=len-1; j>=0; j--) {
        if (str[j] == '1') {
            result += factor;
        }
        factor *= 2;
    }
    return result;
}

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

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

Solving Approach