is_nan

(PHP 4 >= 4.2.0, PHP 5)

is_nan — Finds whether a value is not a number

Description

bool is_nan ( float $val )

Checks whether val is 'not a number', like the result of acos(1.01).

Parameters

val

The value to check

Return Values

Returns TRUE if val is 'not a number', else FALSE.

Examples

Example #1 is_nan() example

<?php
// Invalid calculation, will return a 
// NaN value
$nan = acos(8);

var_dump($nan, is_nan($nan));
?>

The above example will output:

float(NAN)
bool(true)

See Also

• is_finite() - Finds whether a value is a legal finite number
• is_infinite() - Finds whether a value is infinite