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：
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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：
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switch($i){ case 1: echo 1; break; case 2: echo 2; break; default: echo 'others';} |
也可以使用switch来判断一个取值范围，或者说是在case中自定义条件。
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<?phpheader("content-type:text/html;charset=utf8");$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
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<?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
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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···· |
