Java Program to Find the Length of a String Using Recursion

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In this article we are going to see how we can find the length of a string using recursion by Java programming language.

Java Program to Find the Length of a String Using Recursion

The length of the string refers to the total number of characters present in that.

For example-

A string is "BtechGeeks"
Then in this string there are 10 characters. So length of string is 10.

Let’s see the program to find the length of a string using recursion.

Method-1: Java Program to Find the Length of a String Using Recursion By Using Static Input Value

Approach:

  • Store a string.
  • Store the string and call the user-defined method strLen( ) passing the string as parameter.
  • The user defined method checks if we have reached the end, else it recursively calls itself on the same string without the current character and adds 1 to the result.
  • Print the result.

Program:

import java.util.*;
// Main class
public class Main
{
    // Recursive method to calculate string length
    public static int strLen(String s)
    {
        // Checks if we have reached the end of the string
        if (s.equals(""))
            return 0;
        else
            // Calls function on a substring not including the current character
            return strLen(s.substring(1)) + 1;
    }
    
    public static void main(String[] args)
    {
        String s = "Hi!!!";
        // Call the method and store the length
        int length = strLen(s);
        // Print the result
        System.out.println("The number of characters in the string "+s+" is "+length);
    }
}

Output:

The number of characters in the string Hi!!! is 5

Method-2: Java Program to Find the Length of a String Using Recursion By Using User Input Value

Approach:

  • Ask the user to input a string.
  • Store the string and call the user-defined method strLen( ) passing the string as parameter.
  • The user defined method checks if we have reached the end, else it recursively calls itself on the same string without the current character and adds 1 to the result.
  • Print the result.

Program:

import java.util.*;
// Main class
public class Main
{
    // Recursive method to calculate string length
    public static int strLen(String s)
    {
        // Checks if we have reached the end of the string
        if (s.equals(""))
            return 0;
        else
            // Calls function on a substring not including the current character
            return strLen(s.substring(1)) + 1;
    }
    
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        // Ask the user to input the string
        System.out.print("Enter the string - ");
        String s = sc.nextLine();
        // Call the method and store the length
        int length = strLen(s);
        // Print the result
        System.out.println("The number of characters in the string "+s+" is "+length);
    }
}

Output:

Enter the string - helloworld!
The number of characters in the string helloworld! is 11

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