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is_finite	is_nan

Math Functions	Last updated: Mon, 26 Oct 2026

is_infinite

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

is_infinite — Checks whether a float is infinite

Description

function is_infinite(float $num): bool

Returns whether the given num is either INF or -INF.

Parameters

num: The float to check

Return Values

true if num is either INF or -INF, else false.

Examples

Example #1 is_infinite() example

<?php
$inf = 1e308 * 2;

var_dump($inf, is_infinite($inf));

$negative_inf = -$inf;

var_dump($negative_inf, is_infinite($negative_inf));
?>

The above example will output:

float(INF)
bool(true)
float(-INF)
bool(true)

See Also

is_finite() - Checks whether a float is finite
is_nan() - Checks whether a float is NAN

is_finite	is_nan

Math Functions	Last updated: Mon, 26 Oct 2026