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go defer

2022-04-23 20:43:00 【baboon_ chen】

One 、defer principle

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Two 、 Example

1、

package main

import (
	"fmt"
)

func funcA() int {
    
	x := 5
	defer func() {
    
		x += 1
	}()
	return x
}
func main() {
    
	fmt.Println(funcA())
}

/*  Output ：5  reason ： The return value in defer It was determined before  */

2、

func funcB() (x int) {
    
	defer func() {
    
		x += 1
	}()
	return 5
}

/*  Output ：6  reason ： First the 5 Assign a value to x, defer Call again x */

3、

func funcC() (y int) {
    
	x := 5
	defer func() {
    
		x += 1
	}()
	return x
}

/*  Output ：5  reason ： First the 5 Assign a value to y, defer Only change x */

4、

func funcD() (x int) {
    
	defer func(x int) {
    
		x += 1
	}(x)
	return 5
}

/*  Output ：5  reason ： First the 5 Assign a value to x, defer Call again x( Value passed ), What has changed is x Copy of  */