binary_to_decimal.c

#include <assert.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

bool is_binary(intmax_t num);
int num_len(intmax_t num);

int main(void)
{
    intmax_t remainder, number = 0, decimal_number = 0, temp = 1;

    int length = num_len(INTMAX_MAX) - 1;
    printf("\n Enter any binary number , max %d digits: ", length);
    scanf("%jd", &number);
    assert(num_len(number) <= length);
    assert(is_binary(number));

    // Iterate over the number until the end.
    while (number > 0) {
        remainder = number % 10;
        number = number / 10;
        decimal_number += remainder * temp;
        temp = temp * 2; // used as power of 2
    }

    printf("%jd\n", decimal_number);
    return 0;
}

bool is_binary(intmax_t num)
{
    int remainder = 0;

    while (num > 0) {
        remainder = num % 10;
        if (remainder == 0 || remainder == 1) {
            num /= 10;
            continue;
        } else
            return false;
    }
    return true;
}

int num_len(intmax_t num)
{
    int i;
    for (i = 0; num > 0; i++) {
        num /= 10;
    }
    return i;
}