func main() {

	a := []int{7, 8, 9}

	fmt.Printf("%+v\n", a)

	ap(a)

	fmt.Println("==", a)

	app(a)

	fmt.Println("-a-a", a)

}

func ap(a []int) {

	a = append(a, 10)

}

func app(a []int) {

	a[0] = 1

}

package main

import (

	"fmt"

	"runtime"

	"sync"

)

func main() {

	runtime.GOMAXPROCS(1)

	wg := sync.WaitGroup{}

	wg.Add(20)

	for i := 0; i < 10; i++ {

		go func() {

			fmt.Println("i=", i)

			wg.Done()

		}()

	}

	for i := 0; i < 10; i++ {

		go func(i int) {

			fmt.Println("i=", i)

			wg.Done()

		}(i)

	}

	wg.Wait()

}

// demo1 通道误用导致的bug

func demo1() {

	wg := sync.WaitGroup{}

	ch := make(chan int, 10)

	for i := 0; i < 10; i++ {

		ch <- i

	}

	close(ch)

	wg.Add(3)

	for j := 0; j < 3; j++ {

		go func() {

			for {

				task := <-ch

				// 这里假设对接收的数据执行某些操作

				fmt.Println(task)

			}

			wg.Done()

		}()

	}

	wg.Wait()

}