is_long
is_numeric
Variable handling Functions
PHP Manual

# is_null

(PHP 4 >= 4.0.4, PHP 5)

is_null — Finds whether a variable is `NULL`

### Description

bool is_null ( mixed `$var` )

Finds whether the given variable is `NULL`.

### Parameters

`var`

  The variable being evaluated.

### Return Values

Returns `TRUE` if `var` is null, `FALSE` otherwise.

### Examples

Example #1 is_null() example

`<?php
error_reporting(E_ALL);
$foo = NULL;
var_dump(is_null($inexistent), is_null($foo));
?>`

    Notice: Undefined variable: inexistent in ...
    bool(true)
    bool(true)

### See Also

- The `NULL` type
- isset() - Determine if a variable is set and is not NULL
- is_bool() - Finds out whether a variable is a boolean
- is_numeric() - Finds whether a variable is a number or a numeric string
- is_float() - Finds whether the type of a variable is float
- is_int() - Find whether the type of a variable is integer
- is_string() - Find whether the type of a variable is string
- is_object() - Finds whether a variable is an object
- is_array() - Finds whether a variable is an array

is_long
is_numeric
Variable handling Functions
PHP Manual