Question

请帮忙。

for($i=0; $i<12; $i++ ){
        switch($i) {
            case 0:
            case 1:
            case 2:
            case 3:
            case 4:
                echo ("i is less than 5 <br>");
                break;
            case 5:
            case 6:
            case 7:
            case 8:
            case 9:
                echo ("i is less than 10 <br>");
                break;
            default:
                echo ("i is 10 or more <br>");
        }
    }

这是我在Java书中得到的示例代码，我将上面的代码翻译成了PHP。

以下代码的输出：

i is less than 5 
i is less than 5 
i is less than 5 
i is less than 5 
i is less than 5 
i is less than 10 
i is less than 10 
i is less than 10 
i is less than 10 
i is less than 10 
i is 10 or more 
i is 10 or more

我的问题是，如果0到案例3输出“i小于5”，即使它没有任何下面的代码，情况4是带有echo语句的那个，怎么办？我很困惑，有人可以向我解释一下。提前谢谢。

Answer 1

switch应该如何运作。为了不再涉及下一个案例，您必须使用break关键字。我所知道的每种语言都是一样的，包括JavaScript，PHP和Python。

供参考，请查看PHP manual。

Answer 2

想象你的开关就像这样

switch($i) {
            case 0:
               case 1:
                   case 2:
                       case 3:
                          case 4:
                             echo ("i is less than 5 <br>");
                             break;
            case 5:
               case 6:
                 case 7:
                    case 8:
                       case 9:
                         echo ("i is less than 10 <br>");
                         break;
            default:
                echo ("i is 10 or more <br>");

它将一直沿着链子传递，直到打破休息。

适用于For循环PHP的防摔开关盒

2 个答案: