fallthrough：Go里面switch默认相当于每个case最后带有break，匹配成功后不会自动向下执行其他case，而是跳出整个switch, 但是可以使用fallthrough强制执行后面的case代码。
示例程序1：
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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")
}
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输出结果：
The integer was <= 5
The integer was <= 6
The integer was <= 7
The integer was <= 8
问题：是否在switch最后一个分支使用fallthrough？？？
有错误提示，显示：cannot fallthrough final case in switch
fallthrough不能用在switch的最后一个分支。
示例程序2：
上述示例是true、false常量进行分支判断，看如下变量示例。
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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")
}
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输出结果如下：
The integer was <= 5
The integer was <= 6
更改为：
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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")
}
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输出：
default case
总结：
switch分支中使用变量进行判断的时，fallthrough正确的分支开始其作用。
补充：【踩坑】golang的fallthrough大坑
加了fallthrough后，会直接运行【紧跟的后一个】case或default语句，不论条件是否满足都会执行，后面的条件并不会再判断了，?
以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。如有错误或未考虑完全的地方，望不吝赐教。
原文链接：https://www.cnblogs.com/zsy/p/6741902.html