27_Go基础(defer)

package main

import (
    "fmt"
)

// case 1:
func f1() int {
    x := 5
    defer func() {
        x++
    }()
    return x
}

func f2() (x int) {
    defer func() {
        x++
    }()
    return 5
}

func f3() (y int) {
    x := 5
    defer func() {
        x++
    }()
    return x
}
func f4() (x int) {
    defer func(x int) {
        x++
    }(x)
    return 5
}

// case 2:
func calc(index string, a, b int) int {
    ret := a + b
    fmt.Println(index, a, b, ret)
    return ret
}

func main() {
    // case 1:
    fmt.Println(f1()) // 5
    fmt.Println(f2()) // 6
    fmt.Println(f3()) // 5
    fmt.Println(f4()) // 5

    // case 2:
    x := 1
    y := 2
    defer calc("AA", x, calc("A", x, y))
    x = 10
    defer calc("BB", x, calc("B", x, y))
    y = 20

    // A 1 2 3
    // B 10 2 12
    // BB 10 12 22
    // AA 1 3 4
}