1、关闭channel

package mainimport (	"fmt")func main() {	ch := make(chan int) //创建一个无缓存channel	//新建一个goroutine	go func() {		for i := 0; i < 5; i++ {			ch <- i //往通道写数据		}		//不需要再写数据时，关闭channel		close(ch)		//ch <- 666 //关闭channel后无法再发送数据	}() //别忘了()	for {		//如果ok为true，说明管道没有关闭		if num, ok := <-ch; ok == true {			fmt.Println("num = ", num)		} else { //管道关闭			break		}	}}

执行结果：

num =  0num =  1num =  2num =  3num =  4