PHP | is_null() Function (original) (raw)
Last Updated : 05 Oct, 2021
The is_null() function is an inbuilt function in PHP which is used to find whether a variable is NULL or not.
Syntax:
boolean is_null ( $var )
Parameters: This function accepts a single parameter as shown in above syntax and described below.
- $var: Variable to check if it is NULL or not.
Return value: It returns a boolean value. That is, it returns TRUE when $var will be NULL, otherwise it returns FALSE.
Below programs illustrate the is_null() function in PHP:
Program 1:
PHP
<?php
$var1 = NULL;
$var2 = "\0" ;
$var3 = "NULL" ;
$var4 = 0;
is_null ( $var1 ) ? print_r( "True\n" ) : print_r( "False\n" );
is_null ( $var2 ) ? print_r( "True\n" ) : print_r( "False\n" );
is_null ( $var3 ) ? print_r( "True\n" ) : print_r( "False\n" );
is_null ( $var4 ) ? print_r( "True\n" ) : print_r( "False\n" );
?>
Output:
True False False False
Program 2:
PHP
<?php
function check_null( $var )
{
`` return ( is_null ( $var ) ? "True" : "False" );
}
echo check_null(NULL) . "\n" ;
echo check_null(null) . "\n" ;
echo check_null(Null) . "\n" ;
echo check_null(NUll) . "\n" ;
echo check_null(NULl) . "\n" ;
echo check_null(nulL) . "\n" ;
echo check_null(nuLL) . "\n" ;
echo check_null(nULL) . "\n" ;
echo check_null(Nul) . "\n" ;
echo check_null(false) . "\n" ;
?>
Output:
True True True True True True True True False False