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Java program to count number of digits in a string

In this article of java program, we will learn how to count the number of digits in a string Submitted by Jyoti Singh, on October 05, 2017

Problem statement

Given a string and we have to count total number of digits in it using Java.

Example

Input string: "code2017"
Output:
Number of digits: 4

In this code we have one input:

1. An int input (no. of test cases or more clearly the number of strings user wants to check (say 5 i.e user wants to check 5 strings and the program will continue for 5 inputs).
2. A string input (It will be a string entered by the user which needs to be checked).

For each string we will have two outputs

The number of digits in string

Java program to count number of digits in a string

Consider the program: It will take number of inputs, string and print total number of digits.

import java.util.Scanner;

public class CheckDigits {

	public static void main(String[] args) {
		Scanner Kb=new Scanner(System.in);
		System.out.println("How man strings u want to check?");
		//Take the input of no. of test cases
		int t=Kb.nextInt();
		//looping until the test cases are zero
		while(t-->0){
			//Input the string
			System.out.println("Enter the string!");
			String s=Kb.next();
			//counter to count the number of digits in a string
			int digits=0;
			//looping until the string length is zero
			for(int i=0;i<s.length();i++){
				//isDigit is a function of Character class it checks a particular char that whether it is a digit or not
				if(Character.isDigit(s.charAt(i))){
					//counter digit will be incremented each time when a character will be a digit
					digits++;
				}
			}
			//prints the number of digits in a string
			System.out.println(digits);
		}
		System.out.println();
	}

}