循环打印 ABC

package main

import (
	"sync"
	"fmt"
)

var (
	num = 10
)

func main() {
	sig := make(chan int)
	c1 := make(chan string)
	c2 := make(chan string)
	c3 := make(chan string)

	var wg sync.WaitGroup
	wg.Add(3)

	go print(&wg, c1, "A")
	go print(&wg, c2, "B")
	go print(&wg, c3, "C")
	go func() {
		for {
			select {
			case <-sig:
				// 检测到 sig 信号后退出 goroutine，避免出现 Deadlock
				return
			case str := <- c1: {
				fmt.Println(str)
				str = <- c2
				fmt.Println(str)
				str = <- c3
				fmt.Println(str)
			}
			}
		}
	}()
	wg.Wait()
	sig <- 1
}

func print(wg *sync.WaitGroup, c chan string, str string) {
	defer wg.Done()

	for i := 0; i < num; i++ {
		c <- str
	}
}