Traversing and Summing Even Digits in Go

Welcome to another exciting session! In today's lesson, we delve into a unique coding challenge using Go. We will traverse the digits of a number using a for loop under specific conditions. This exercise will help you sharpen your skills in working with Go loops and conditional statements, both of which are fundamental building blocks of programming in Go. Are you ready to get started?

Our mission today is intriguing! We need to create a function that calculates the sum of even-numbered digits from a given integer. We'll avoid converting the integer to a string at any point. For example, given the number 4625, our function should return 12, which is the sum of the even digits 4, 6, and 2.

The integer n will always be positive and within the range of 1 to $10^8$. Are you prepared for this challenge? Fantastic! Let's begin our journey into coding with Go!

We start by setting up the basic structure for our function. In this initial step, we define a variable digitSum that will accumulate the sum of the even digits.

Here's how we begin:

func solution(n int) int {
    var digitSum int
    // The function expands from here.
}

Recall that in Go, we can mimic a while loop using a for loop by specifying only the condition. We use this approach to iterate through the digits of the integer n as long as n is greater than zero. This allows us to process each digit from the least significant to the most significant.

Integrating this into our function, we have:

func solution(n int) int {
    var digitSum int
    for n > 0 {  // Equivalent to a while loop
        // Further development of the function will proceed here.
    }
}

This for loop iterates until the condition n > 0 is no longer satisfied, effectively serving the same purpose as a while loop in other languages.

Inside our loop, we'll extract the last digit of n using the modulo operation (n % 10). If this digit is even, we'll add it to digitSum. After processing this digit, we truncate it from n using integer division (n / 10). This prepares the loop for the next digit.

Here's what our code looks like now:

func solution(n int) int {
    var digitSum int
    for n > 0 {
        digit := n % 10
        if digit % 2 == 0 {  // Check if the digit is even.
            digitSum += digit
        }
        n = n / 10 // Remove the last digit.
    }
}