php中switch语句用法详解

PHP编程
switch (expression)
{
case label1:
 code to be executed if expression = label1;
 break; 
case label2:
 code to be executed if expression = label2;
 break;
default:
 code to be executed
 if expression is different from both label1 and label2;
}

PHP编程
switch($i){
  case 1:
    echo 1;
    break;
  case 2:
    echo 2;
    break;
  default:
    echo 'others';
}

PHP编程
<?php
header("content-type:text/html;charset=utf8");
$score=50;
switch($score) 
{
 case $score>=90 && $score<=100:
  echo "优<br>";
  break;
 case $score>=80 && $score<90:
  echo "良<br>";
  break;
 case $score>=70 && $score<80:
  echo "中<br>";
  break;
 case $score>=60 && $score<70:
  echo "及格<br>";
  break;
 case $score>=0 && $score<60:
  echo "不及格<br>";
  break;
 default:
  echo"成绩输入差错<br>";
}
?>

PHP编程
<?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/>'.'胜利退出????'; 
 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/>'.'胜利退出????'; 
 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/>'.'胜利退出????'; 
 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/>'.'胜利退出????'; 
 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/>'.'胜利退出????'; 
 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/>'.'胜利退出????'; 
 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/>'.'胜利退出????'; 
 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/>'.'胜利退出????'; 
 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/>'.'胜利退出????'; 
 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/>'.'胜利退出????'; 
 echo '<hr/>'; 
?> 

PHP编程
hello1
胜利退出????
hello2
胜利退出????
hello3
胜利退出????
hello4
胜利退出????
hello5
胜利退出????
hello6
胜利退出????
hello7
胜利退出????
hello81
胜利退出????
我是5号出口hello61
胜利退出????
hello6我是2号出口
胜利退出????