fallthrough：Go里面switch默認(rèn)相當(dāng)于每個(gè)case最后帶有break，匹配成功后不會(huì)自動(dòng)向下執(zhí)行其他case，而是跳出整個(gè)switch, 但是可以使用fallthrough強(qiáng)制執(zhí)行后面的case代碼。
示例程序1：
switch {
case false:
fmt.Println("The integer was = 4")
fallthrough
case true:
fmt.Println("The integer was = 5")
fallthrough
case false:
fmt.Println("The integer was = 6")
fallthrough
case true:
fmt.Println("The integer was = 7")
fallthrough
case false:
fmt.Println("The integer was = 8")
default:
fmt.Println("default case")
}
輸出結(jié)果：
The integer was = 5
The integer was = 6
The integer was = 7
The integer was = 8
問(wèn)題：是否在switch最后一個(gè)分支使用fallthrough？？？
有錯(cuò)誤提示，顯示：cannot fallthrough final case in switch
fallthrough不能用在switch的最后一個(gè)分支。
示例程序2：
上述示例是true、false常量進(jìn)行分支判斷，看如下變量示例。
s := "abcd"
switch s[1] {
case 'a':
fmt.Println("The integer was = 4")
fallthrough
case 'b':
fmt.Println("The integer was = 5")
fallthrough
case 'c':
fmt.Println("The integer was = 6")
default:
fmt.Println("default case")
}
輸出結(jié)果如下：
The integer was = 5
The integer was = 6
更改為：
s := "abcd"
switch s[3] {
case 'a':
fmt.Println("The integer was = 4")
fallthrough
case 'b':
fmt.Println("The integer was = 5")
fallthrough
case 'c':
fmt.Println("The integer was = 6")
default:
fmt.Println("default case")
}
輸出：
default case
總結(jié)：
switch分支中使用變量進(jìn)行判斷的時(shí)，fallthrough正確的分支開(kāi)始其作用。
補(bǔ)充：【踩坑】golang的fallthrough大坑
加了fallthrough后，會(huì)直接運(yùn)行【緊跟的后一個(gè)】case或default語(yǔ)句，不論條件是否滿足都會(huì)執(zhí)行，后面的條件并不會(huì)再判斷了，?
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