go和php中的switch對比

php

<?php
$k = 6;
switch($k){
	case 4:
		var_dump("was <= 4");
	case 5:
		var_dump("was <= 5");
	case 6:
		var_dump("was <= 6");
	case 7:
		var_dump("was <= 7");
	case 8:
		var_dump("was <= 8");
	default:
		var_dump("default case");
}
?>

output
string(8) “was <= 6”
string(8) “was <= 7”
string(8) “was <= 8”
string(12) “default case”

加上break

<?php
$k = 6;
switch($k){
	case 4:
		var_dump("was <= 4");
		break;
	case 5:
		var_dump("was <= 5");
		break;
	case 6:
		var_dump("was <= 6");
		break;
	case 7:
		var_dump("was <= 7");
		break;
	case 8:
		var_dump("was <= 8");
		break;
	default:
		var_dump("default case");
}
?>

output
string(8) “was <= 6”

go

package main

import (
	"fmt"
)

type byte uint8

func main() {
	te()
}

func te() {
	k := 6
	switch k {
	case 4:
		fmt.Println("was <= 4")
	case 5:
		fmt.Println("was <= 5")
	case 6:
		fmt.Println("was <= 6")
	case 7:
		fmt.Println("was <= 7")
	case 8:
		fmt.Println("was <= 8")
	default:
		fmt.Println("default case")
	}
}

output
was <= 6

加上fallthrough

package main

import (
	"fmt"
)

type byte uint8

func main() {
	te()
}

func te() {
	k := 6
	switch k {
	case 4:
		fmt.Println("was <= 4")
		fallthrough
	case 5:
		fmt.Println("was <= 5")
		fallthrough
	case 6:
		fmt.Println("was <= 6")
		fallthrough
	case 7:
		fmt.Println("was <= 7")
		fallthrough
	case 8:
		fmt.Println("was <= 8")
		fallthrough
	default:
		fmt.Println("default case")
	}
}

output
was <= 6
was <= 7
was <= 8
default case

總結

• go中加上了默認break，匹配到對應case，在執行完相應代碼後就會退出整個 switch 代碼塊
• go中用fallthrough關鍵字繼續執行後續分支的代碼