PHP is_null() function PHP

By using the is_null function, we can check whether the variable is NULL or not. This function was introduced in PHP 4.0.4.

SYNATX:

1. bool is_null ( mixed $var )  

Parameter

Return Type:

The PHP is_null() function returns true if var is null, otherwise false.

Important Note:

We can unset the variable value by using the unset function.

Example 1

1. <?php  
2.     $var1 = TRUE;  
3.     if (is_null($var1))  
4.         {  
5.             echo 'Variable is  NULL';  
6.         }  
7.         else  
8.         {  
9.             echo 'Variable is not NULL';  
10.         }  
11. ?>  

Example 2

1. <?php  
2.     $x= 100;  
3.     unset($x);  
4.     echo is_null($x);  
5. ?>  

Example 3

1. <?php    
2.     $x = NULL;   
3.     $y = "\0";  
4.     is_null($x) ? print_r("True\n") : print_r("False\n");  
5.     echo "<br/>";  
6.     is_null($y) ? print_r("True\n") : print_r("False\n");  
7. ?>