Question

(C++ only) Write a function that returns a decimal number from a binary string. The function header is as follows:

int bin2Dec(const string& binaryString)

For example, bin2Dec("10001") returns 17.

Write a test program that prompts the user to enter a binary number as a string and displays its decimal equivalent value

Sample Input: 1110100110101

Sample Output: Enter a bianry number: 1110100110101

7477

Answer 1

#include <iostream>
#include <string>
using namespace std;

int bin2Dec(const string& binaryString) {
    if (binaryString.empty()) {
        return 0;
    } else {
        return 2*bin2Dec(binaryString.substr(0, binaryString.size()-1)) + (binaryString[binaryString.size()-1]-'0');
    }
}

int main() {
    string s;
    cout << "Enter a binary number: ";
    cin >> s;
    cout << bin2Dec(s) << endl;
    return 0;
}