Select with multiple channels in Go - Mini Project: Build & Apply

Select with multiple channels

📖 Scenario: You are building a simple program that listens to two different message channels. Each channel sends a message at different times. You want to print the message as soon as it arrives from either channel.

🎯 Goal: Create two channels that send messages, then use a select statement to wait for messages from both channels and print them as they arrive.

📋 What You'll Learn

Create two channels called chan1 and chan2 of type chan string

Create a variable called done of type chan bool to signal when to stop

Use a select statement inside a for loop to receive messages from chan1 and chan2

Print the message received from either channel with fmt.Println

Stop the loop after receiving 2 messages total and send true to done

💡 Why This Matters

🌍 Real World

Listening to multiple data sources or events at the same time is common in real-world programs like servers, chat apps, or sensors.

💼 Career

Understanding how to use Go channels and select statements is important for writing concurrent programs and working with real-time data streams.

1

Create two string channels

Create two channels called chan1 and chan2 of type chan string.

Go

# Create two channels called chan1 and chan2 of type chan string
// Your code here

Hint

Use make(chan string) to create a channel of strings.

2

Create a done channel to signal completion

Add a channel called done of type chan bool to signal when to stop the program.

Go

package main

func main() {
    chan1 := make(chan string)
    chan2 := make(chan string)
    // Create a done channel of type chan bool
    // Your code here
}

Hint

Use make(chan bool) to create the done channel.

3

Use select to receive messages from both channels

Write a for loop with a select statement to receive messages from chan1 and chan2. Use variables msg1 and msg2 to receive messages. Count the total messages received in a variable called count.

Go

package main

func main() {
    chan1 := make(chan string)
    chan2 := make(chan string)
    done := make(chan bool, 1)

    // Use a for loop with select to receive messages from chan1 and chan2
    // Your code here
}

Hint

Use select inside a for loop to wait for messages from both channels.

4

Print messages and stop after two messages

Print the messages received from chan1 and chan2 using fmt.Println. Stop the loop after receiving 2 messages and send true to done. Also, add a line to receive from done to prevent the program from exiting early.

Go

package main

import "fmt"

func main() {
    chan1 := make(chan string)
    chan2 := make(chan string)
    done := make(chan bool, 1)

    count := 0

    go func() {
        chan1 <- "Message from chan1"
    }()

    go func() {
        chan2 <- "Message from chan2"
    }()

    for {
        select {
        case msg1 := <-chan1:
            fmt.Println(msg1)
            count++
        case msg2 := <-chan2:
            fmt.Println(msg2)
            count++
        }
        if count == 2 {
            done <- true
            break
        }
    }

    // Wait for done signal to prevent program exit
    // Your code here
}

Hint

Use <-done to wait for the done signal before exiting.