is_nan()

is_nan() — Checks whether a float is NAN.

Built-in function of PHP 8.5. The manual lists it as available in PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

What it does

Returns whether the given num is NAN (Not A Number).

Signature

is_nan(float $num): bool

Parameters

Return value

true if num is NAN, else false.

Example

A runnable snippet:

$nan = sqrt(-1); var_dump($nan, is_nan($nan));

Output:

float(NAN) bool(true)

See also

is_finite(), is_infinite()

All PHP 8.5 built-in functions

Reference card built from the PHP manual page is_nan() (PHP documentation, CC BY 3.0). The page is generated from the manual, so the wording of the parameter and return value text follows php.net.