func add (n *int , isok chan bool){
	for i :=0 ;i <1000 ; i ++ {
		*n = *n + 1
	}
	isok <- true
}
func main () {
	var ok = make(chan bool , 2)
	var i,u = 0,0
	go add(&i , ok)
	go add(&i , ok)
	for <- ok {
		u++
		if u == 2 {
			break
		}
	}
	fmt.Println(i)
}

func add (n *int , wait *sync.WaitGroup) {
 for i := 0 ; i <1000 ; i ++ {
  *n = *n + 1
 }
 defer wait.Done()
}
func main () {
  var wait sync.WaitGroup
 var i = 0
 wait.Add(2)
  go add(&i , &wait)
 go add(&i , &wait)
 wait.Wait()
 fmt.Println(i)
 }

type Wait struct {//創(chuàng)建一個(gè)結(jié)構(gòu)體
 Num int//線程的個(gè)數(shù)
 ok chan bool//線程與函數(shù)通信的管道
}
func (t *Wait) Add (n int){//初始化線程個(gè)數(shù)
 t.Num = n
 t.ok = make(chan bool , n)
}
func (t *Wait) Done (){//執(zhí)行完一個(gè)線程之后，執(zhí)行的函數(shù)，每執(zhí)行完一個(gè)線程，調(diào)用函數(shù)，使用通信管道進(jìn)行傳輸一個(gè)true
 t.ok <- true
}
func (t *Wait) Wait () {//等待函數(shù)，每次管道中放入一個(gè)true，說明，執(zhí)行完一個(gè)線程，t.Num--，如果等于0說明所有線程執(zhí)行結(jié)束
 for <- t.ok {
  t.Num--
  if t.Num == 0 {
   break
  }
 }
}

package main 
import (
    "fmt"
    "sync"
)
 
func father(wg *sync.WaitGroup) {
    wg.Add(1)
    defer wg.Done()
 
    fmt.Printf("father\n")
    for i := 0; i < 10; i++ {
        go child(wg, i)
    }
}
 
func child(wg *sync.WaitGroup, id int) {
    wg.Add(1)
    defer wg.Done()
 
    fmt.Printf("child [%d]\n", id)
}
 
func main() {
    var wg sync.WaitGroup
    go father(&wg)
 
    wg.Wait()
    log.Printf("main: father and all chindren exit")
}

father
main: father and all chindren exit
child [9]
child [0]
child [4]
child [7]
child [8]

package main 
import (
    "fmt"
    "sync"
)
 
func father(wg *sync.WaitGroup) {
    defer wg.Done()
 
    fmt.Printf("father\n")
    for i := 0; i < 10; i++ {
        wg.Add(1)
        go child(wg, i)
    }
}
 
func child(wg *sync.WaitGroup, id int) {
    defer wg.Done()
    fmt.Printf("child [%d]\n", id)
}
 
func main() {
    var wg sync.WaitGroup
    wg.Add(1)
    go father(&wg)
 
    wg.Wait()
    fmt.Println("main: father and all chindren exit")
}

father
child [9]
child [7]
child [8]
child [1]
child [4]
child [5]
child [2]
child [6]
child [0]
child [3]
main: father and all chindren exit