Traversing Digits and Summing Even Numbers in C#

Introduction

Welcome! In today's lesson, we'll delve into a unique coding challenge that centers around traversing the digits of a number using a while loop under a specific condition. You'll have the opportunity to practice and enhance your skills in working with C#'s loops and conditional statements — fundamental concepts in programming. Are you as excited as I am? Let's dive in!

Task Statement

Today, our objective is to create a method that operates on an integer input. The task might seem simple, but it requires some ingenuity. Here's the mission: given an integer, n, we need to calculate and return the sum of its even digits — and here's the clincher — without converting n into a string. For instance, if n equals 4625, the output should be 12 because the sum of the even digits 4, 6, and 2 equals 12 . Keep in mind that n will always be a positive integer between 1 and 100,000,000. Ready to give it a shot? Great! Let's get started!

Solution Building: Step 1

To start, we need the basic structure of our method, where we begin by defining a variable digitSum to keep track of the sum of even digits. Below is the initial platform for our method: C# public class Solution {public int SumEvenDigits(int n) {int digitSum = 0; // Our code will evolve from here return digitSum;}}

Step 2: Setting up the Loop

The tool we've chosen to traverse through the digits of the input integer n is the while loop, which is set to run as long as n is greater than zero. Let's incorporate this into our method: C# public class Solution {public int SumEvenDigits(int n) {int digitSum = 0; while (n > 0) {// We'll develop our method from here} return digitSum;}}

Step 3: Extracting and Processing Each Digit

Inside our loop, we'll first extract the last digit of n using the modulo operation (n % 10). If the digit is even, we'll increase our digitSum by this digit. After processing a digit, we'll then chop off the last digit of n using integer division (n / 10), which allows the while loop to proceed to the next digit. Here's how this appears in the code: C# public class Solution {public int SumEvenDigits(int n) {int digitSum = 0; while (n > 0) {int digit = n % 10; if (digit % 2 == 0) { // Check if the digit is even digitSum += digit;} n = n / 10; // Remove the last digit}}}

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After summing up all the even digits, the final step is to return our digitSum.

Our complete method now looks like this:

public class Solution {
    public int SumEvenDigits(int n) {
        int digitSum = 0;
        while (n > 0) {
            int digit = n % 10;
            if (digit % 2 == 0) {  // Check if the digit is even
                digitSum += digit;
            }
            n = n / 10;  // Remove the last digit
        }
        return digitSum;
    }
}

public class Solution {
    public int SumEvenDigits(int n) {
        int digitSum = 0;
        while (n > 0) {
            int digit = n % 10;
            if (digit % 2 == 0) {  // Check if the digit is even
                digitSum += digit;
            }
            n = n / 10;  // Remove the last digit
        }
        return digitSum;
    }
}

To run our code and see it in action, we need to include a Main method. This method will create an instance of the Solution class, call SumEvenDigits with a test value, and print the result.

Here is the complete code with the Main method:

using System;

public class Solution {
    public int SumEvenDigits(int n) {
        int digitSum = 0;
        while (n > 0) {
            int digit = n % 10;
            if (digit % 2 == 0) {  // Check if the digit is even
                digitSum += digit;
            }
            n = n / 10;  // Remove the last digit
        }
        return digitSum;
    }

    public static void Main(string[] args) {
        Solution solution = new Solution();
        int result = solution.SumEvenDigits(4625);
        Console.WriteLine("Sum of even digits: " + result);  // Output should be "Sum of even digits: 12"
    }
}

using System;

public class Solution {
    public int SumEvenDigits(int n) {
        int digitSum = 0;
        while (n > 0) {
            int digit = n % 10;
            if (digit % 2 == 0) {  // Check if the digit is even
                digitSum += digit;
            }
            n = n / 10;  // Remove the last digit
        }
        return digitSum;
    }

    public static void Main(string[] args) {
        Solution solution = new Solution();
        int result = solution.SumEvenDigits(4625);
        Console.WriteLine("Sum of even digits: " + result);  // Output should be "Sum of even digits: 12"
    }
}

Well done on completing this lesson! You've successfully navigated the foundational concepts of using a while loop to traverse the digits of a number and have gained an understanding of how to apply conditions within it. Now it's your turn to apply what you've learned. I invite you to explore additional challenges to solidify and build upon your new skill set. Remember, the only limit to your growth is the boundary of your dedication. Keep practicing; your C# prowess is growing with each challenge you conquer!

Introduction

Task Statement

Solution Building: Step 1

Step 2: Setting up the Loop

Step 3: Extracting and Processing Each Digit

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Step 4: Returning the Result

Adding a Main Method to Run the Code

Lesson Summary