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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

Previous: is_long
Next: is_numeric



PHP: Tips of the Day

SQL injection that gets around mysql_real_escape_string()

Consider the following query:

$iId = mysql_real_escape_string("1 OR 1=1");    
$sSql = "SELECT * FROM table WHERE id = $iId";

mysql_real_escape_string() will not protect you against this. The fact that you use single quotes (' ') around your variables inside your query is what protects you against this. The following is also an option:

$iId = (int)"1 OR 1=1";
$sSql = "SELECT * FROM table WHERE id = $iId";

Ref : https://bit.ly/32q3bJ7