Convert Binary String to Integer Without strtol function or Libraries

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

uint16_t binary_to_uint(const char *str) {
    uint16_t r = 0;
    for (int i = 0; str[i] != '\0'; i++) {
        if (str[i] - '0') {
            r = r << 1;
            r |= 1;
        } else {
            r = r << 1;
        }
    }
    return r;
}

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

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