英文:
What is the back arrow "<-" in Golang?
问题
我在一小段代码中使用它来使time.After()函数生效，如果没有它，程序将直接执行下一行代码，而不会等待计时器完成。
以下是示例代码：
package main
import (
"fmt"
"time"
)
func main() {
a := 1
fmt.Println("Starting")
<-time.After(time.Second * 2)
fmt.Println("Printed after 2 seconds")
}
英文:
I used it in a small piece of code to make time.After() work, without it the program simply goes on to the next line without waiting for the timer to finish.
This is the example:
package main
import (
"fmt"
"time"
)
func main() {
a := 1
fmt.Println("Starting")
<-time.After(time.Second * 2)
fmt.Println("Printed after 2 seconds")
}
答案1
得分: 14
<- 运算符用于等待通道的响应。在这段代码中，它用于等待由 time.After 提供的通道，在经过 X 时间后将被填充。
你可以在 Go 之旅 中了解更多关于通道的知识，这是 @Marc 提到的。请注意，如果你不处理多个通道结果（使用 select），<-time.After(time.Second * 2) 可以被同步的 time.Sleep(time.Second * 2) 语句替代。
time.After 通常用于在涉及一个或多个通道的异步操作中设置结果超时，类似于以下示例：
func doLongCalculations() (int, error) {
resultchan := make(chan int)
defer close(resultchan)
go calculateSomething(resultchan)
select {
case <-time.After(time.Second * 2):
return nil, fmt.Errorf("操作超时")
case result := <-resultchan:
return result, nil
}
}
再次强烈建议你参加 Go 之旅，以了解 Go 的基础知识 
英文:
The <- operator is used to wait for a response of a channel. It is used in this code to wait for a channel provided by the time.After that will be fed after X amount of time.
You can know more about channels in the tour of Go that @Marc mentioned. And note that <-time.After(time.Second * 2) can be replaced with the synchronous time.Sleep(time.Second * 2) statement, if you're not dealing with multiple channel results (with as select).
The time.After is usually used when timing out a result from a asynchronous operation involving one or more channels, something like this:
func doLongCalculations() (int, error) {
resultchan := make(chan int)
defer close(resultchan)
go calculateSomething(resultchan)
select {
case <-time.After(time.Second * 2):
return nil, fmt.Errorf("operation timed out")
case result := <-resultchan
return result, nil
}
}
Again, we highly recommend you to take the tour of Go to get to know Go's basics
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