Default case in select in Go - Mini Project: Build & Apply

Default Case in Select

📖 Scenario: Imagine you are building a simple Go program that listens to two channels for messages. Sometimes, no messages arrive, and you want to handle that situation gracefully without blocking your program.

🎯 Goal: You will create a Go program that uses a select statement with a default case. This default case will run when no channels are ready, allowing the program to continue working without waiting.

📋 What You'll Learn

Create two channels named chan1 and chan2.

Create a select statement that listens to both channels.

Add a default case in the select to handle when no channels have data.

Print messages to show which case ran.

💡 Why This Matters

🌍 Real World

Channels and select statements are used in Go programs to handle multiple tasks at the same time, like waiting for user input, network messages, or timers.

💼 Career

Understanding how to use <code>select</code> with a <code>default</code> case is important for writing efficient and responsive Go programs, a skill valued in backend development and systems programming.

1

Create two channels

Create two channels called chan1 and chan2 that can send and receive strings.

Go

// Your code here

Hint

Use make(chan string) to create each channel.

2

Add a select statement with default case

Add a select statement inside main that listens to chan1 and chan2. Add a default case that prints "No messages received".

Go

package main

func main() {
    chan1 := make(chan string)
    chan2 := make(chan string)

    // Add select statement with default case here
}

Hint

Use select with case for each channel and a default case for no messages.

3

Send a message to chan1

Before the select statement, start a new goroutine that sends the string "hello" to chan1.

Go

package main

import "fmt"

func main() {
    chan1 := make(chan string)
    chan2 := make(chan string)

    // Start a goroutine to send "hello" to chan1

    select {
    case msg1 := <-chan1:
        fmt.Println("Received from chan1:", msg1)
    case msg2 := <-chan2:
        fmt.Println("Received from chan2:", msg2)
    default:
        fmt.Println("No messages received")
    }
}

Hint

Use a goroutine with go func() { chan1 <- "hello" }() to send the message.

4

Print the result

Run the program and print the output. The program should print Received from chan1: hello.

Go

package main

import "fmt"

func main() {
    chan1 := make(chan string)
    chan2 := make(chan string)

    go func() {
        chan1 <- "hello"
    }()

    select {
    case msg1 := <-chan1:
        fmt.Println("Received from chan1:", msg1)
    case msg2 := <-chan2:
        fmt.Println("Received from chan2:", msg2)
    default:
        fmt.Println("No messages received")
    }
}

// Run the program to see the output

Hint

Run the program. It should print Received from chan1: hello.