php：switch的用法实例分享

switch 语句类似于具有同一个表达式的一系列 if 语句。很多场合下需要把同一个变量（或表达式）与很多不同的值比较，并根据它等于哪个值来执行不同的代码。这正是 switch 语句的用途。

Note: 注意和其它语言不同，continue 语句作用到 switch 上的作用类似于 break。如果在循环中有一个 switch 并希望 continue 到外层循环中的下一轮循环，用 continue 2。

Note:

注意 switch/case 作的是松散比较。

实例：

<?php
  //switch细节
  //情况一：数值匹配的时候自动转换成字串
  $a=1;
  switch($a){
    case "1":
		echo &#39;hello1&#39;;
		break;
	default:
		echo &#39;sorry none is the same!&#39;;
		break;
  }
  echo &#39;<br/>&#39;.&#39;成功退出····&#39;;
  echo &#39;<hr/>&#39;;
   //情况二：数值匹配的时候自动转换成字符
  $a=1;
  switch($a){
    case &#39;1&#39;:
		echo &#39;hello2&#39;;
		break;
	default:
		echo &#39;sorry none is the same!&#39;;
		break;
  }
  echo &#39;<br/>&#39;.&#39;成功退出····&#39;;
  echo &#39;<hr/>&#39;;
   //情况三：字符匹配的时候自动转换成数值
  $a=&#39;1&#39;;
  switch($a){
    case 1:
		echo &#39;hello3&#39;;
		break;
	default:
		echo &#39;sorry none is the same!&#39;;
		break;
  }
  echo &#39;<br/>&#39;.&#39;成功退出····&#39;;
  echo &#39;<hr/>&#39;;
   //情况四：字串匹配的时候自动转换成数值
  $a="1";
  switch($a){
    case 1:
		echo &#39;hello4&#39;;
		break;
	default:
		echo &#39;sorry none is the same!&#39;;
		break;
  }
  echo &#39;<br/>&#39;.&#39;成功退出····&#39;;
  echo &#39;<hr/>&#39;;
   //情况五：float也可以匹配
  $a=1.1;
  switch($a){
    case 1.1:
		echo &#39;hello5&#39;;
		break;
	default:
		echo &#39;sorry none is the same!&#39;;
		break;
  }
  echo &#39;<br/>&#39;.&#39;成功退出····&#39;;
  echo &#39;<hr/>&#39;;
   //情况六：非0是true
  $a=true;
  switch($a){
    case 1:
		echo &#39;hello6&#39;;
		break;
	case true:
		echo &#39;hello61&#39;;
		break;
	default:
		echo &#39;sorry none is the same!&#39;;
		break;
  }
  echo &#39;<br/>&#39;.&#39;成功退出····&#39;;
  echo &#39;<hr/>&#39;;
   //情况七：能匹配boolean
  $a=true;
  switch($a){
    case true:
		echo &#39;hello7&#39;;
		break;
	case 2:
		echo &#39;hello71&#39;;
		break;
	default:
		echo &#39;sorry none is the same!&#39;;
		break;
  }
  echo &#39;<br/>&#39;.&#39;成功退出····&#39;;
  echo &#39;<hr/>&#39;;
   //情况八：能匹配null
  $a=null;
  switch($a){
    case 2://&#39;&#39;  ""  false 0 都能进入
		echo &#39;hello8&#39;;
		break;
	case null:
		echo &#39;hello81&#39;;
		break;
	default:
		echo &#39;sorry none is the same!&#39;;
		break;
  }
  echo &#39;<br/>&#39;.&#39;成功退出····&#39;;
  echo &#39;<hr/>&#39;;
   //情况九：退出顺序
  $a=5;
  switch($a){
    case 1:
		echo &#39;hello6&#39;;
		break;
	case 2:
		echo &#39;我是2号出口&#39;;
		break;
	case 5:
		echo &#39;我是5号出口&#39;;
		//break;
	case true:
		echo &#39;hello61&#39;;
		break;
	default:
		echo &#39;sorry none is the same!&#39;;
		break;
  }
  echo &#39;<br/>&#39;.&#39;成功退出····&#39;;
  echo &#39;<hr/>&#39;;
   //情况十：退出顺序
  $a=50;
  switch($a){
	default:
		echo &#39;sorry none is the same!&#39;;
		//break;
    case 50:
		echo &#39;hello6&#39;;
		//break;
	case 2:
		echo &#39;我是2号出口&#39;;
		break;
	case 5:
		echo &#39;我是5号出口&#39;;
		//break;
	case 6:
		echo &#39;hello61&#39;;
		break;
  }
  echo &#39;<br/>&#39;.&#39;成功退出····&#39;;
  echo &#39;<hr/>&#39;;
?>

hello1
成功退出····

---

hello2
成功退出····

---

hello3
成功退出····

---

hello4
成功退出····

---

hello5
成功退出····

---

hello6
成功退出····

---

hello7
成功退出····

---

hello81
成功退出····

---

我是5号出口hello61
成功退出····

---

hello6我是2号出口
成功退出····

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