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What is the difference between isset() and empty() in php
- 王林Original
- 2020-06-29 16:23:214673browse
The difference between isset() and empty() in php is: isset() function is used to detect whether the variable is set, the syntax format is: [isset (mixed var)]; empty() function is used to determine the value Whether it is empty, the syntax format is: [empty(mixed var)].
isset() function
isset() function is generally used to detect whether a variable is set.
Format:
bool isset ( mixed var [, mixed var [, ...]] )
Return value:
If the variable does not exist, it returns FALSE;
If the variable exists and its value is NULL, it also returns FALSE ;
If the variable exists and the value is not NULL, TRUE is returned;
When multiple variables are checked at the same time, TRUE is returned only when each single item meets the previous requirement, otherwise the result is FALSE .
empty() function
empty() function is used to determine whether the value is empty.
Format:
bool empty ( mixed var )
Return value:
If the variable does not exist, it returns TRUE;
If the variable exists and its value is "", 0, "0", NULL,, FALSE, array(), var $var; and objects without any attributes, return TRUE;
If the variable exists and the value is not "", 0, "0", NULL, FALSE, array(), var $var; and objects without any attributes, return FALSE.
Example: Simple comparison of empty() and isset()
<?php
$var = 0;
// 结果为 true，因为 $var 为空
if (empty($var)) {
echo '$var is either 0 or not set at all';
}
// 结果为 false，因为 $var 已设置
if (!isset($var)) {
echo '$var is not set at all';
}
?>Note: empty() only detects variables, and detecting anything that is not a variable will cause a parsing error.
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