Return inside loops in Go - Mini Project: Build & Apply

Return inside loops

📖 Scenario: Imagine you are checking a list of numbers to find the first even number. Once you find it, you want to stop checking and return that number immediately.

🎯 Goal: You will write a Go function that loops through a slice of integers and returns the first even number it finds. If no even number is found, it returns -1.

📋 What You'll Learn

Create a slice of integers named numbers with the values 3, 7, 10, 5, 8.

Create a function called firstEven that takes a slice of integers as input and returns an integer.

Inside firstEven, use a for loop with index i and value num to iterate over the slice.

Inside the loop, use an if statement to check if num is even (divisible by 2). If yes, return num immediately.

If the loop finishes without finding an even number, return -1.

In main, call firstEven(numbers) and print the returned value.

💡 Why This Matters

🌍 Real World

Finding the first item that meets a condition quickly is common in many programs, like searching for available seats, checking for errors, or validating inputs.

💼 Career

Understanding how to return early from loops helps write efficient code and is a common pattern in software development jobs.

1

Create the numbers slice

Create a slice of integers called numbers with the exact values 3, 7, 10, 5, 8.

Go

var numbers = []int{3, 7, 10, 5, 8} // Your code here

Need a hint?

Use var numbers = []int{3, 7, 10, 5, 8} to create the slice.

2

Create the firstEven function

Create a function called firstEven that takes a parameter nums of type []int and returns an int.

Go

package main

var numbers = []int{3, 7, 10, 5, 8}

func firstEven(nums []int) int {
    // Your code here
}

Need a hint?

Define the function with func firstEven(nums []int) int and return an integer.

3

Add loop and return inside firstEven

Inside the firstEven function, use a for loop with variables i and num to iterate over nums. Inside the loop, use an if statement to check if num % 2 == 0. If yes, return num immediately.

Go

package main

var numbers = []int{3, 7, 10, 5, 8}

func firstEven(nums []int) int {
    for i, num := range nums {
        // Your code here
    }
    return -1
}

Need a hint?

Use for i, num := range nums and inside it check if num%2 == 0 then return num.

4

Call firstEven and print the result

In the main function, call firstEven(numbers) and print the returned value using fmt.Println. Remember to import fmt.

Go

package main

import "fmt"

var numbers = []int{3, 7, 10, 5, 8}

func firstEven(nums []int) int {
    for i, num := range nums {
        if num%2 == 0 {
            return num
        }
    }
    return -1
}

func main() {
    // Your code here
}

Need a hint?

Use result := firstEven(numbers) and then fmt.Println(result) inside main.