使开关使用===比较而不==比较在PHP中 [英] make switch use === comparison not == comparison In PHP

问题描述

有没有办法做到这一点，以便下面的代码仍然使用开关并返回b而不是a?谢谢！

Is there anyway to make it so that the following code still uses a switch and returns b not a? Thanks!

$var = 0;
switch($var) {
    case NULL : return 'a'; break;
    default : return 'b'; break;
}

当然，使用if语句是这样的:

Using if statements, of course, you'd do it like this:

$var = 0;
if($var === NULL) return 'a';
else return 'b';

但是对于更复杂的示例，这变得很冗长.

But for more complex examples, this becomes verbose.

推荐答案

对不起，您不能在switch语句中使用===比较，因为根据

Sorry, you cannot use a === comparison in a switch statement, since according to the switch() documentation:

请注意，开关/大小写比较松散.

Note that switch/case does loose comparison.

这意味着您必须提出解决方法.来自 松散比较表 ，则可以通过类型转换来利用NULL == "0"为假的事实:

This means you'll have to come up with a workaround. From the loose comparisons table, you could make use of the fact that NULL == "0" is false by type casting:

<?php
$var = 0;
switch((string)$var) 
{
    case "" : echo 'a'; break; // This tests for NULL or empty string   
    default : echo 'b'; break; // Everything else, including zero
}
// Output: 'b'
?>

实时演示

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