1、使用两个goroutine交替、顺序打印一段字符串的字符

输入：hello world

输出：hello world

关键点：控制goroutine的执行先后循序

golang语言版本：

package main

import (
	"fmt"
	"sync"
)

func main() {
	content := "hello world"
	var wg sync.WaitGroup //打印完后再退出主goroutine
	var count = len(content)
	wg.Add(count)

	ch1 := make(chan string, 1)
	ch2 := make(chan string, 1)
	ch1 <- "1"

	for _, v := range content {
		select { //监听并选择有值的通道进行处理
		case <-ch1:
			go func(s string) {
				defer wg.Done()
				fmt.Println(s)
				ch2 <- "2"
			}(string(v))
		case <-ch2:
			go func(s string) {
				defer wg.Done()
				fmt.Println(s)
				ch1 <- "1"
			}(string(v))
		}
	}

	wg.Wait()
}

输出：