php中switch语句用法详解 |
|
本文标签：php,switch语句 本文介绍php中的switch语句的用法，它跟其他语句中的switch用法差不多的，但注意有有一个break语句 。 PHP中switch语句的标准语法：
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;
}
举例：
switch($i){
case 1:
echo 1;
break;
case 2:
echo 2;
break;
default:
echo others;
}
也可以使用switch来判断一个取值范围，或者说是在case中自定义条件 。
<?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"成绩输入错误<br>";
}
?>
简单示例
<?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 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/>;
?>
运行结果 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···· |
