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 res=0;
    for(int i=0;*(str+i) != '\0';i++){
        res = res << 1;   // shift left
        if (*(str+i) == '1') {
            res |= 1;        // set last bit
        }
    }
    return res;
}

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

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