is_nan

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

is_nan — Finds whether a value is not a number

Description

is_nan(float $num): bool

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

Parameters

num

The value to check

Return Values

Returns true if num 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