w3resource

PHP: is_null() function

Description

The is_null () function is used to test whether a variable is NULL or not.

Version:

(PHP 4 and above)

Syntax:

is_null (var_name)

Parameter:

Name Description Required /
Optional		 Type
var_name The variable being checked Required Mixed*

*Mixed: Mixed indicates that a parameter may accept multiple (but not necessarily all) types.

Return value:

Returns TRUE if var_name is null, FALSE otherwise.

Value Type: Boolean

Example:

<?php
$var_name = TRUE;
if (is_null($var_name))
{
echo 'Variable is  NULL';
}
else
{
echo 'Variable is not NULL';
}
?>

Output:

Variable is not NULL

View the example in the browser

Practice here online:

See also

PHP Function Reference

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Next: is_numeric



PHP: Tips of the Day

PHP - how to create a newline character?

Only double quoted strings interpret the escape sequences \r and \n as '0x0D' and '0x0A' respectively, so you want:

"\r\n"

Single quoted strings, on the other hand, only know the escape sequences \\ and \'.

So unless you concatenate the single quoted string with a line break generated elsewhere (e. g., using double quoted string "\r\n" or using chr function chr(0x0D).chr(0x0A)), the only other way to have a line break within a single quoted string is to literally type it with your editor:

$s = 'some text before the line break
some text after';

Make sure to check your editor for its line break settings if you require some specific character sequence (\r\n for example).

Ref : https://bit.ly/3hcyege