go语言学习记录2

defer ：

1 函数离开前执行

2 FILO 栈

package main

import "fmt"

func trace(s string) {
	fmt.Println("entering:", s);
}

func untrace(s string) {
	fmt.Println("leaving:", s);
}

func a() {
	trace("a");
	defer untrace("a");
	fmt.Println("in a")
}

func b() {
	trace("b");
	defer untrace("b");
	fmt.Println("in b");
	a()
}

func trace2(s string) string {
	fmt.Println("entering:",s)
	return s
}

func un(s string) {
	fmt.Println("leaving:",s)
}

func a2() {
	defer un(trace2("a"))
	fmt.Println("in a")
}

func b2() {
	defer un(trace2("b"))
	fmt.Println("in b")
	a2()
}

func main() {
	for i:=0;i<5;i++{
		defer fmt.Println(i)
	}
	b2();
}

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