in_array()不起作用 [英] in_array() does not work

问题描述

为什么会返回true.

Why does this return true.

$needle = TRUE;
$haystack = array('that', 'this');

print in_array($needle, $haystack); // 1

我知道人们可以通过 in_array()严格参数来检查类型.我想知道为什么，具体表现出我展示的行为.

I am aware that one can pass in_array() the strict parameter to check types. I want to know why specifically the behaviour I show is exhibited.

推荐答案

在进行松散比较(即忽略类型)时，PHP中的任何非空字符串都等于 TRUE .您可以通过以下方法进行测试:

Any non-empty string in PHP is equal to TRUE when loose comparison is made (i.e. type is ignored). You may test this by doing:

var_dump('this' == TRUE);
var_dump('that' == TRUE);

演示

但是，如果进行严格比较(即考虑类型)，结果会大不相同:

But the results are quite different when strict comparison is made (i.e. type is taken into consideration):

var_dump('this' === TRUE);
var_dump('that' === TRUE);

演示

为了在功能 in_array ，则必须将可选的第三个参数设置为 TRUE :

$needle = TRUE;
$haystack = array('that', 'this');

var_dump(in_array($needle, $haystack, TRUE));

演示

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