在php中，为什么empty("0")返回true? [英] in php, why empty("0") returns true?

问题描述

根据php文档，调用empty($var)

According to php documentation, the following expressions return true when calling empty($var)

• "(一个空字符串)
• 0(0为整数)
• 0.0(浮点数为0)
• "0"(0作为字符串)
• NULL
• 假
• array()(一个空数组)
• $ var; (已声明变量，但没有值)

• "" (an empty string)
• 0 (0 as an integer)
• 0.0 (0 as a float)
• "0" (0 as a string)
• NULL
• FALSE
• array() (an empty array)
• $var; (a variable declared, but without a value)

我已经找到了如何通过使用empty($var) && $var != 0解决"问题的方法，但是为什么php开发人员做到了呢? 我认为这很荒谬，请支持以下代码:

i've found how to "solve" the problem by using empty($var) && $var != 0 but why php developers did it? i think it is ridiculous, suppouse you have this code:

if (empty($_POST["X"])) {
    doSomething();
}

我认为"0"不为空，什么也没有时为空！！！ 也许最好使用

i think "0" is not empty, empty is when there is nothing!!! maybe it's better to use

if (isset($x) && x != "") {//for strings
    doSomething();
}

推荐答案

empty 大致镜像

转换为布尔值时，以下值为FALSE:

When converting to boolean, the following values are considered FALSE:

• 布尔值FALSE本身
• 整数0(零)
• 浮点数0.0(零)
• 空字符串和字符串"0"
• 具有零个元素的数组
• ...

• the boolean FALSE itself
• the integer 0 (zero)
• the float 0.0 (zero)
• the empty string, and the string "0"
• an array with zero elements
• ...

就为什么这样工作，或者为什么空函数也随之工作-嗯，就是这样.

As far as why PHP works this way, or why the empty function followed suit - well, that's Just The Way It Is.

考虑使用strlen($x)(这尤其适合$_POST等都是字符串值的源)来确定是否存在非空字符串，包括"0".

Consider using strlen($x) (this is especially well-suited to sources like $_POST which are all string values) to determine if there is a non-empty string, including "0".

然后，我使用的最终形式将是:isset($x) && strlen($x)，在知道有一些个帖子数据的情况下，进行了任何其他处理.

The final form I use would then be: isset($x) && strlen($x), with any additional processing applied knowing there was some post data.

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