In this tutorial, we will learn about the select statement in Go.
The select statement blocks the code and waits for multiple channel operations simultaneously.
A select blocks until one of its cases can run, then it executes that case. It chooses one at random if multiple are ready.
package main
import (
"fmt"
"time"
)
func main() {
one := make(chan string)
two := make(chan string)
go func() {
time.Sleep(time.Second * 2)
one <- "One"
}()
go func() {
time.Sleep(time.Second * 1)
two <- "Two"
}()
select {
case result := <-one:
fmt.Println("Received:", result)
case result := <-two:
fmt.Println("Received:", result)
}
close(one)
close(two)
}
Similar to switch , select also has a default case that runs if no other case is ready. This will help us send or receive without blocking.
func main() {
one := make(chan string)
two := make(chan string)
for x := 0; x < 10; x++ {
go func() {
time.Sleep(time.Second * 2)
one <- "One"
}()
go func() {
time.Sleep(time.Second * 1)
two <- "Two"
}()
}
for x := 0; x < 10; x++ {
select {
case result := <-one:
fmt.Println("Received:", result)
case result := <-two:
fmt.Println("Received:", result)
default:
fmt.Println("Default...")
time.Sleep(200 * time.Millisecond)
}
}
close(one)
close(two)
}
It's also important to know that an empty select {} blocks forever.
func main() {
...
select {}
close(one)
close(two)
}
This article is part of my open source Go Course available on Github.
karanpratapsingh
/
learn-go
Master the fundamentals and advanced features of the Go programming language
Learn Go
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This course is also available on my website and as an ebook on leanpub. Please leave a ⭐ as motivation if this was helpful!
Table of contents
-
Getting Started
-
Chapter I
-
Chapter II
-
Chapter III
-
Chapter IV
-
Appendix
What is Go?
Go (also known as Golang) is a programming language developed at Google in 2007 and open-sourced in 2009.
It focuses on simplicity, reliability, and efficiency. It was designed to combine the efficacy, speed…
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