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In php, empty means "empty", is a built-in function to check whether a variable is empty, the syntax "empty ($var)"; when a variable value is 0, empty string, "0.0", "0", NULL, FALSE, empty array, empty () thinks that the variable is equal to empty.

Operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

Empty means "empty".

Empty () is a built-in function in php that determines whether a variable is "empty".

Empty also detects whether the variable is empty or zero. When the value of a variable is 0 zero empty (), the variable is considered to be equivalent to empty, which means that it is not set.

Example:

$id=0;empty ($id)? print "It's empty.": print "It's $id."; / / result: It's empty .print "

";! isset ($id)? print" It's empty. ": print" It's $id. "; / / result: It's 0.

When a variable does not exist, or when its value is equal to FALSE, then it is considered nonexistent. Empty () does not generate a warning if the variable does not exist.

Note: prior to PHP 5.5, empty () only supported variables; anything else would cause a parsing error. In other words, the following code will not take effect:

Empty (trim ($name))

Instead, you should use:

Trim ($name) = = false

Empty () does not generate a warning, even if the variable does not exist. This means that empty () is essentially equivalent to! isset ($var) | | $var = = false.

Return value:

Returns FALSE if var exists and is a non-empty non-zero value. Otherwise, TRUE is returned.

The following variables are considered empty:

"" (empty string)

0 (0 as an integer)

0.0 (as 0 of a floating point number)

"0" (as 0 of the string)

NULL

FALSE

Array () (an empty array)

$var; (a variable that is declared but has no value)

Example:

Output:

$ivar1 is empty or 0. The $istr1 string is not empty or 0. The above is about the content of this article on "how to use empty in php". I believe we all have a certain understanding. I hope the content shared by the editor will be helpful to you. If you want to know more about the relevant knowledge, please follow the industry information channel.

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