Golang学习笔记之延迟函数(defer)的使用小结

func a() {
  i := 0
  defer fmt.Println(i) //输出0，因为i此时就是0
  i++
  defer fmt.Println(i) //输出1，因为i此时就是1
  return
}

func main() {
  defer fmt.Println(\"1\")
  defer fmt.Println(\"2\")
  defer fmt.Println(\"3\")
  defer fmt.Println(\"4\")
}

name := \"Naveen你好\"
  fmt.Printf(\"%s\\n\", string(name))
  fmt.Printf(\"逆序:\")
  defer fmt.Printf(\"\\n\")
  for _, v := range []rune(name) {
    defer fmt.Printf(\"%c\", v)
  }

func (r rect) area(wg *sync.WaitGroup) {
  if r.length < 0 {
    fmt.Printf(\"rect %v\'s length should be greater than zero\\n\", r)
    wg.Done()
    return
  }
  if r.width < 0 {
    fmt.Printf(\"rect %v\'s width should be greater than zero\\n\", r)
    wg.Done()
    return
  }
  area := r.length * r.width
  fmt.Printf(\"rect %v\'s area %d\\n\", r, area)
  wg.Done()
}

func (r rect) area(wg *sync.WaitGroup) {
  defer wg.Done()
  if r.length < 0 {
    fmt.Printf(\"rect %v\'s length should be greater than zero\\n\", r)
    return
  }
  if r.width < 0 {
    fmt.Printf(\"rect %v\'s width should be greater than zero\\n\", r)
    return
  }
  area := r.length * r.width
  fmt.Printf(\"rect %v\'s area %d\\n\", r, area)
}

package main 
import \"fmt\" 
func deferTest(number int) int {
 defer func() {
 number++
 fmt.Println(\"three:\", number)
 }()
 
 defer func() {
 number++
 fmt.Println(\"two:\", number)
 }()
 
 defer func() {
 number++
 fmt.Println(\"one:\", number)
 }()
 
 return number
}
 
func main() {
 fmt.Println(\"函数返回值：\", deferTest(0))
}