Program for length of a string using recursion

Given a string calculate length of the string using recursion. 

Examples:

Input : str = "abcd"
Output :4

Input : str = "GEEKSFORGEEKS"
Output :13

We have discussed 5 Different methods to find length of a string in C++
How to find length of a string without string.h and loop in C?

Algorithm:

recLen(str)
{
   If str is NULL 
       return 0
   Else 
      return 1 + recLen(str + 1)
}

Implementation:

C++

// CPP program to calculate length of
// a string using recursion
#include <bits/stdc++.h>
using namespace std;

/* Function to calculate length */
int recLen(char* str)
{
    // if we reach at the end of the string
    if (*str == '\0')
        return 0;
    else
        return 1 + recLen(str + 1);
}

/* Driver program to test above function */
int main()
{
    char str[] = "GeeksforGeeks";
    cout << recLen(str);
    return 0;
}

Java

// java program to calculate length of
// a string using recursion
import java.util.*;

public class GFG{

    /* Function to calculate length */
    private static int recLen(String str)
    {

        // if we reach at the end of the string
        if (str.equals(""))
            return 0;
        else
            return recLen(str.substring(1)) + 1;
    }

    /* Driver program to test above function */
    public static void main(String[] args)
    {


        String str ="GeeksforGeeks";
        System.out.println(recLen(str));
    }
}

// This code is contributed by Sam007.

Python3

# Python program to calculate
# length of a string using
# recursion
str = "GeeksforGeeks"

# Function to
# calculate length
def string_length(str) :

    # if we reach at the
    # end of the string
    if str == '':
        return 0
    else :
        return 1 + string_length(str[1:])

# Driver Code
print (string_length(str))

# This code is contributed by
# Prabhjeet

C#

// C# program to calculate length of
// a string using recursion
using System;

public class GFG{

    /* Function to calculate length */
    private static int recLen(string str)
    {

        // if we reach at the end of the string
        if (str.Equals(""))
            return 0;
        else
            return recLen(str.Substring(1)) + 1;
    }

    /* Driver program to test above function */
    public static void Main()
    {


        string str ="GeeksforGeeks";
        Console.WriteLine(recLen(str));
    }
}

// This code is contributed by vt_m.

PHP

<?php
// PHP program to calculate
// length of a string using
// recursion

// Function to
// calculate length
function recLen(&$str, $i)
{
    // if we reach at the
    // end of the string
    if ($i == strlen($str))
        return 0;
    else
        return 1 +
               recLen($str,
                      $i + 1);
}

// Driver Code
$str = "GeeksforGeeks";
echo (recLen($str, 0));

// This code is contributed by
// Manish Shaw(manishshaw1)
?>

Javascript

<script>

// JavaScript program to calculate length of
// a string using recursion

/* Function to calculate length */
    function recLen(str)
    {

        // if we reach at the end of the string
        if (str == "")
            return 0;
        else
            return recLen(str.substring(1)) + 1;
    }

// Driver code

        let str ="GeeksforGeeks";
        document.write(recLen(str));

</script>

Output

13

Time Complexity : O(n) 
Auxiliary Space : O(n) for recursion call stack. 

Since this solution requires extra space and function call overhead, it is not recommended to use it in practice.