先说说switch()语句的格式
switch(表达式){
case 匹配1:
当匹配1和表达式匹配成功执行的代码;
break;
case 匹配2:
当匹配2和表达式匹配成功执行的代码;
break;
default:
如果case语句没有与表达式成功所执行的代码;
}
理解 switch 是怎样执行的非常重要。switch 语句一行接一行地执行(实际上是语句接语句)。开始时没有代码被执行。仅当一个 case 语句中的值和 switch 表达式的值匹配时 PHP 才开始执行语句,直到 switch 的程序段结束或者遇到第一个 break 语句为止。如果不在 case 的语句段最后写上 break 的话,PHP 将继续执行下一个 case 中的语句段。
例子:
复制代码 代码如下:
switch($i){
case 1:
echo "$i的值是1";
break;
case 2:
echo "$i的值是2";
break;
case 3:
echo "$i的值是3";
break;
default:
echo "$i的值不是1、2、3";
}
?>
在一个 case 中的语句也可以为空,这样只不过将控制转移到了下一个 case 中的语句,知道下一个case的语句块不为空,这样就实现了多个值匹配同意代码块:
当$i的值为1或2或3时输出同一语句:
复制代码 代码如下:
switch($i){
case 1:
case 2:
case 3:
echo "$i的值为$i的值为1或2或3";
break;
}
?>

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