代码实例说明php中switch的用法

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