PHP switch-case语句中的默认情况并不真正作为默认值？ [英] default case in a PHP switch-case statement doesn't really work as the default?
问题描述
我正在使用以下PHP代码，在用户提交的页面上提交了一个带有某个 foo 输入名称的表单，这个PHP代码进程，并决定相应转发用户的URL。
I'm using the following PHP code, on a page that a user reach on after submitting a form with a certain foo input name in it, which this PHP code processes, and decides to which URL that user be forwarded accordingly.
我刚注意到，如果用户没有输入带的页面foo 输入名称（例如，假设前一页上的表单有'vvv'作为输入名称，而不是因为某些错误），
那么这个PHP代码就不会发送用户使用默认URL。相反，它会在循环中每隔3秒刷新一次。
I've just noticed that If a user does not enter that page with an foo input name (for example, let's say the form on the previous page had a `vvv' as the input name instead, due to some error),
then this PHP code would not send the user to the default URL. instead, it would refresh itself every 3 seconds in a loop.
为什么？如果有任何错误，包括上述情况，不应该获得默认值吗？
Why? shouldn't the default value be obtained in case of any error, including the above scenario?
代码：
<?php
if(isset($_POST['foo'])){
switch ($_POST['foo']) {
case "aaa":
$url = "http://www.aaa.com/";
break;
default:
$url = "http://www.bbb.com/";
}
}
header( "refresh:3;url=$url" );
?>
<!doctype html>
<html>
<head>
<style>
.test {display: block;}
</style>
</head>
<body>
test
</body>
</html>
推荐答案
$ _ POST [' foo'] 有什么价值吗？
尝试转储该值以检查其中是否有任何内容：
Does $_POST['foo'] has any value at all?
Try dump the value to check if there is anything in it:
var_dump($_POST['foo'])
如果结果为null，则表单中有错误。
If the result of this is null then there is an error in your form.
这样的事情应该有效：
<form method='post' action = $this->url()>
<div>
<input type='text' name='foo' value='foo'>
</div>
<div>
<input type='submit' value='submit' name='submit'>
</div>
</form>
行动：
if(isset($_POST['foo']) && !empty($_POST['foo'])){
switch ($_POST['foo']) {
case "aaa":
$url = "http://www.aaa.com/";
break;
default:
$url = "http://www.bbb.com/";
}
}
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