4.4 Go goto continue break

4.4 Go goto continue break

Go language goto statement unconditional jump to a specified line of code.

goto statement is generally used in combination with conditional statements, conditions to achieve escape out of the loop and the like.

Go program 不推荐使用goto, so as to avoid procedural confusion, difficult to read.

Example:

package main

import "fmt"

func main() {
    var num int = 100

    fmt.Println("num值100")
    if num > 90 {
        goto label
        //此处代码已经不走，直接goto了
        fmt.Println("呵呵")
    }
    fmt.Println("我是占位符")
    fmt.Println("我是占位符")
    fmt.Println("我是占位符")
    fmt.Println("我是占位符")
    fmt.Println("我是占位符")
    //触发了goto，进入本次标签
label:
    fmt.Println("由于触发了goto，进入到我这里了")

    fmt.Println("我也是占位符")
    fmt.Println("我也是占位符")
    fmt.Println("我也是占位符")
}

1.1. break

For 中断当前循环or跳出switch中的case语句

package main

import "fmt"

func main() {
    var num int = 10

    for num < 50 {
        fmt.Printf("a的值是：%v\n", num)
        num++
        if num > 30 {
            break //跳出for循环
        }
    }
}

break label

When the for-loop is nested, nested directly out all cycles can be used to break label characteristic

package main

import (
    "fmt"
)

func main() {
    fmt.Println("主程序开始执行")
Exit:
    for i := 0; i < 9; i++ {
        for j := 0; j < 9; j++ {
            if i+j > 15 {
                fmt.Println("程序结束")
                break Exit
            }
        }
    }
    fmt.Println("已跳出循环体")
}

1.2. Continue statement

continue statement residual bit out of the current cycle, the next cycle continues.

package main

import "fmt"

func main() {
    /* 定义局部变量 */
    var a int = 10

    /* for 循环 */
    for a < 20 {
        if a == 15 {
            /* 当a等于15时，跳出循环，让a++，等于16，跳过本次循环 */
            a++
            continue
        }
        fmt.Printf("a 的值为 : %d\n", a)
        a++
    }
}

1.3. Return statement

return used in the method or function, or a method where the termination represents a function (method and function).

return in the main function, the main function indicates the termination, the termination procedure.

package main

import "fmt"

func main() {
    for i := 0; i <= 10; i++ {
        if i == 5 {
            return //直接退出main函数了
        }
        fmt.Printf("本次循环次数：%d\n", i)
    }
    //永远走不带这里了，第五次for循环时候，直接return了
    fmt.Println("循环结束，走到了我")
}