Detailed explanation of php empty() function to check whether the variable is empty

empty() only detects variables, detecting anything that is not a variable will result in a parsing error. In other words, the following statements will have no effect: empty(addslashes($name))

empty — Checks whether a variable is empty

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bool empty (mixed $var)
If var is a non-empty or non-zero value, empty() returns FALSE. In other words, "", 0, "0", NULL, FALSE, array(), var $var; and objects without any attributes will be considered empty , returns TRUE if var is empty.

In addition to not generating a warning when the variable is not set, empty() is the antonym of (boolean) var. See Converting to Boolean for more information.

Example #1 A simple comparison between empty() and isset().

The code is as follows:

<?php 
$var = 0; 
// 结果为 true，因为 $var 为空 
if (empty($var)) { 
echo &#39;$var is either 0 or not set at all&#39;; 
} 
// 结果为 false，因为 $var 已设置 
if (!isset($var)) { 
echo &#39;$var is not set at all&#39;; 
} 
?>

Note: Because it is a language constructor rather than a function, it cannot be called by the variable function .

Note:

empty() only tests variables, testing anything that is not a variable will result in a parsing error. In other words, the following statement will not work: empty(addslashes($name)).

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