What does empty mean in php?

#What does empty mean in php?

empty means empty, it is a built-in function in php, used to check whether a variable is empty.

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

empty() After version 5.5, it supports expressions, not just variables.

Version requirements: PHP 4, PHP 5, PHP 7

Basic syntax:

empty ( $var )

Parameters: empty() The function accepts a single argument, as shown in the syntax above, as described below.

$ var: Variable used to check if it is empty.

Return value: Return false when $var exists and has a non-null non-zero value. Otherwise return true.

Note: Under PHP 5.5, the empty() function only supports variable checking, and anything else will cause a parsing error.

Simple example of empty() function

Let’s use an example to introduce how the empty() function uses to determine whether a variable is empty

<?php 
header("content-type:text/html;charset=utf-8");
echo "<br>";
$var1 = NULL; 
$var2 = ""; 
$var3 = "PHP中文网"; 
empty($var1) ? print_r("变量var1为空<br>") : print_r("变量var1不为空<br>"); 
  
empty($var2) ? print_r("变量var2为空<br>") : print_r("变量var2不为空<br>"); 
empty($var3) ? print_r("变量var3为空<br>") : print_r("变量var2不为空，值为：".$var3); 
?>

Output:

Explanation:

The following will be used by the empty() function Values ​​considered null:

1, "" (empty string)

2, 0 (0 as an integer)

3, 0.0 (0 as a floating point number )

4, "0" (0 as a string)

5, null

6, false

7, array() (an empty Array)

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