Convert Binary String to Integer Without strtol function or Libraries

Code

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

uint16_t binary_to_uint(const char *str) {
    
    uint8_t index_counter = 0;

    uint16_t num = 0x0;

    for(uint8_t i=strlen(str); str[i]>=0; i--)
    {
        if(str[i]=='1' || str[i]=='0')
        {
            if(str[i]=='1')
            {
                num+= 1 * (pow(2,index_counter));
            }

            index_counter++;
        }
    }

    return num;
}

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

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

Solving Approach