is_finite

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

is_finite —Checks whether a float is finite

Description

is_finite(float$num):bool

Returns whether the givennum is a finite float.

A finite float is neitherNAN (is_nan()), nor infinite (is_infinite()).

Parameters

num: Thefloat to check

Return Values

true ifnum is none ofNAN,INF, -INF, elsefalse.

Examples

Example #1is_finite() example

<?php
$float=1.2345;
var_dump($float,is_finite($float));

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

$inf=1e308*2;
var_dump($inf,is_finite($inf));
?>

The above example will output:

float(1.2345)bool(true)float(NAN)bool(false)float(INF)bool(false)

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User Contributed Notes1 note

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Daniel Klein ¶

8 years ago

(is_finite($float)) is equivalent to (!is_infinite($float) && !is_nan($float)), i.e. a number can only be one of finite, infinite and NaN. You don't need to check both is_infinite() and is_nan() to see if a number is invalid or out of range.

<?php
$finite=42;
$infinite=log(0);
$nan=acos(2);

var_dump(is_finite($finite),is_infinite($finite),is_nan($finite));// true, false, false
var_dump(is_finite($infinite),is_infinite($infinite),is_nan($infinite));// false, true, false
var_dump(is_finite($nan),is_infinite($nan),is_nan($nan));// false, false, true
?>