Java Program to Count the Digits of a Number Using Recursion

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In this article we are going to see how we can count the digits of a number using recursion by Java programming language.

Java Program to Count the Digits of a Number Using Recursion

Let’s see the program.

Method-1: Java Program to Count the Digits of a Number Using Recursion By Using Static Input Value

Approach:

  • Create a static integer variable ‘ctr’ and store any number in it.
  • Call the user defined method calcDigits( ) and store the result in an integer  variable ‘digits’
  • So calcDigits( ) is an user-defined method that increments the counter and calls the method by dividing the digits by 10.
  • Print the result.

Program:

import java.util.*;
// Main class
public class Main
{
    // counter to store the count
    static int ctr=0;
    // Method to count the number of digits in a number using recursion
    public static int calcDigits(int num)
    {
        // Till number is greater than zero keep on incrementing the counter
        if(num!=0)
        {
            ctr++;
            // Divides the number by 10 and recursively calls the method
            calcDigits(num/10);
        }
        return ctr;
    }
    
    public static void main(String[] args)
    {
        int num = 3962;
        // Call the method and store the result
        int digits = calcDigits(num);
        // Print the result
        System.out.println("The number of digits in "+num+" is "+digits);
    }
}

Output:

The number of digits in 3962 is 4

Method-2: Java Program to Count the Digits of a Number Using Recursion By Using User Input Value

Approach:

  • Create a static integer variable ‘ctr‘
  • Ask the user to enter a number and store it in an integer variable ‘num‘
  • Call the user defined method calcDigits( )and store the result in an integer  variable ‘digits’
  • So calcDigits( ) is an user-defined method that increments the counter and calls the method by dividing the digits by 10.
  • Print the result.

Program:

import java.util.*;
// Main class
public class Main
{
    // counter to store the count
    static int ctr=0;
    // Method to count the number of digits in a number using recursion
    public static int calcDigits(int num)
    {
        // Till number is greater than zero keep on incrementing the counter
        if(num!=0)
        {
            ctr++;
            // Divides the number by 10 and recursively calls the method
            calcDigits(num/10);
        }
        return ctr;
    }
    
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter the number to calculate its digits - ");
        int num = sc.nextInt();
        // Call the method and store the result
        int digits = calcDigits(num);
        // Print the result
        System.out.println("The number of digits in "+num+" is "+digits);
    }
}

Output:

Enter the number to calculate its digits - 965
The number of digits in 965 is 3

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