GoLang switch 控制语句的灵活应用

与我们以前接触过的switch 控制语句不同，GoLang 的switch 语句使用更灵活。

简单使用示例

score := 79
switch score / 10 {
    case 9:
        rz = "优秀"
        fallthrough  // 表示继续执行下面的Case而不是退出Switch
    case 8:
        rz = "良好"
    case 7:
        rz = "一般"
        break //可以添加
    case 6:
        rz = "及格"
    default:
        rz = "不及格"
 }

使用说明：

• switch 的判断条件可以是任何数据类型
• 在每个case 里可以不用break 退出，默认退出
• 可以通过关键字 fallthrough 让switch 不退出，而继续判断下面的case

如果多个匹配结果所对应的代码段一样，则可以在一个case中并列出所有的匹配项

switch ch {
    case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
        cl = "Int"
    case 'A', 'B', 'C', 'D',  'a', 'b', 'c', 'd', 'e':
        cl = "ABC"
    default:
        cl = "Other Char"
}

switch可以没有表达式，在 Case 中使用布尔表达式，这样形如 if-else

func GetConstellation(month, day int) (star string) {
    switch {
    case month <= 0, month >= 13, day <= 0, day >= 32:
        star = "-1"
    case (month == 1 && day >= 20), (month == 2 && day <= 18):
        star = "水瓶座"
    case (month == 2 && day >= 19), (month == 3 && day <= 20):
        star = "双鱼座"
    case (month == 3 && day >= 21), (month == 4 && day <= 19):
        star = "白羊座"
    case (month == 4 && day >= 20), (month == 5 && day <= 20):
        star = "金牛座"
    case (month == 5 && day >= 21), (month == 6 && day <= 21):
        star = "双子座"
    case (month == 6 && day >= 22), (month == 7 && day <= 22):
        star = "巨蟹座"
    case (month == 7 && day >= 23), (month == 8 && day <= 22):
        star = "狮子座"
    case (month == 8 && day >= 23), (month == 9 && day <= 22):
        star = "处女座"
    case (month == 9 && day >= 23), (month == 10 && day <= 22):
        star = "天秤座"
    case (month == 10 && day >= 23), (month == 11 && day <= 21):
        star = "天蝎座"
    case (month == 11 && day >= 22), (month == 12 && day <= 21):
        star = "射手座"
    case (month == 12 && day >= 22), (month == 1 && day <= 19):
        star = "魔蝎座"
    }
    return
}