Recursive Program for Binary to Decimal

Given a binary number as string, find its decimal equivalent.

Examples:

Input :  binary = "101"
Output :   5

Input :  binary = "1111"
Output :   15

We have discussed iterative solution to convert Binary to Decimal.

The idea is simple, we add current term and recur for remaining terms.

binary2decimal

C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// Recursive CPP program to convert binary 
// decimal
#include<bits/stdc++.h>
using namespace std;
  
int toDecimal(string binary, int i=0)
{
    // If we reached last character
    int n = binary.length();
    if (i == n-1)
      return binary[i] - '0';
      
    // Add current tern and recur for
    // remaining terms
    return ((binary[i] - '0') << (n-i-1))  +
            toDecimal(binary, i+1);
}
  
// Driver code
int main()
{
    string binary = "1010";
    cout << toDecimal(binary) << endl;
    return 0;
}

chevron_right


Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// Recursive Java program to convert binary 
// decimal
  
  
class GFG
{
    static int toDecimal(String binary,int i)
    {
        // If we reached last character
        int n = binary.length();
        if (i == n-1)
        return binary.charAt(i) - '0';
          
        // Add current tern and recur for
        // remaining terms
        return ((binary.charAt(i) - '0') << (n-i-1)) +
                toDecimal(binary, i+1);
    }
      
    // Driver code
    public static void main(String []args)
    {
        String binary = "1010";
        int i=0;
        System.out.println(toDecimal(binary,i));
          
    }
  
}
  
// This code is contributed 
// by ihritik ( Hritik Raj)

chevron_right


Python3

filter_none

edit
close

play_arrow

link
brightness_4
code

# Recursive Python3 program to convert 
# binary decimal 
  
def toDecimal(binary, i = 0):
  
    # If we reached last character 
    n = len(binary) 
    if (i == n - 1) :
        return int(binary[i]) - 0
      
    # Add current tern and recur for 
    # remaining terms 
    return (((int(binary[i]) - 0) << (n - i - 1)) + 
                        toDecimal(binary, i + 1))
  
# Driver code 
if __name__ == "__main__" :
      
    binary = "1010"
    print(toDecimal(binary))
  
# This code is contributed by Ryuga

chevron_right


C#

filter_none

edit
close

play_arrow

link
brightness_4
code

// Recursive C# program to convert binary 
// decimal
  
  
using System;
class GFG
{
    static int toDecimal(string binary, int i=0)
    {
        // If we reached last character
        int n = binary.Length;
        if (i == n-1)
        return binary[i] - '0';
          
        // Add current tern and recur for
        // remaining terms
        return ((binary[i] - '0') << (n-i-1)) +
                toDecimal(binary, i+1);
    }
      
    // Driver code
    public static void Main()
    {
        string binary = "1010";
        Console.WriteLine(toDecimal(binary));
          
    }
  
}
  
// This code is contributed 
// by ihritik ( Hritik Raj)

chevron_right


PHP

filter_none

edit
close

play_arrow

link
brightness_4
code

<?php 
// Recursive CPP program to convert 
// binary decimal
  
function toDecimal($binary, $i = 0)
{
    // If we reached last character
    $n = strlen($binary);
    if ($i == $n - 1)
    return ord($binary[$i]) - ord('0');
      
    // Add current tern and recur for
    // remaining terms
    return ((ord($binary[$i]) - ord('0')) << ($n - $i - 1)) +
             toDecimal($binary, $i + 1);
}
  
// Driver code
$binary = "1010";
echo toDecimal($binary) . "\n";
  
// This code is contributed by ita_c
?>

chevron_right


Output:

10


My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.



Improved By : AnkitRai01, Ita_c, ihritik