php:检查数组中的某些项目是否为空 [英] php: check if certain item in an array is empty
问题描述
在 PHP 中,如何检查数组中的指定项(按名称,我认为 - 数字也可能有效)是否为空?
In PHP, how would one check to see if a specified item (by name, I think - number would probably also work) in an array is empty?
推荐答案
空类型(来自 PHP 手册).以下对于任何变量都被认为是空的:
Types of empty (from PHP Manual). The following are considered empty for any variable:
- ""(空字符串)
- 0(0 作为整数)
- "0" (0 作为字符串)
- 空
- 错误
- array()(空数组)
- var $var;(声明了一个变量,但在类中没有值)
请看下面的例子:
$arr = array(
'ele1' => 'test',
'ele2' => false
);
1) $arr['ele3'] 未设置.所以:isset($arr['ele3']) === false &&empty($arr['ele3']) === true
它未设置且为空.empty() 检查变量是否已设置且是否为空.
1) $arr['ele3'] is not set. So:
isset($arr['ele3']) === false && empty($arr['ele3']) === true
it is not set and empty. empty() checks for whether the variable is set and empty or not.
2) $arr['ele2'] 已设置,但为空.所以:isset($arr['ele2']) === true &&empty($arr['ele2']) === true
2) $arr['ele2'] is set, but empty. So:
isset($arr['ele2']) === true && empty($arr['ele2']) === true
1) $arr['ele1'] 已设置且不为空:isset($arr['ele1']) === true &&empty($arr['ele1']) === false
1) $arr['ele1'] is set and not empty:
isset($arr['ele1']) === true && empty($arr['ele1']) === false
如果您想检查它是否为空,只需使用 empty() 函数即可.
if you wish to check whether is it empty, simply use the empty() function.
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