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php: Sharing usage examples of switch

黄舟

Release： 2023-03-11 11:18:02

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switch statement is similar to a series of if statements with the same expression. There are many situations where you need to compare the same variable (or expression) with many different values and execute different code depending on which value it equals. This is exactly what the switch statement is for.

Note: Note that unlike other languages, the continue statement acts similarly to break when applied to switch. If you have a switch in a loop and want to continue to the next loop in the outer loop, use continue 2.

Note:

Note that switch/case does a loose comparison.

Example:

<?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;;
?>

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hello1
Exit successfully····

##hello2

Exit successfully····

hello3

Exit successfully····

hello4

Exit successfully····

hello5

Exit successfully ····

hello6

Successfully exited····

hello7

Successfully exited····

hello81

Exited successfully····

I am Exit No. 5hello61

Exited successfully····

hello6I am Exit No. 2

Exited successfully····

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