is_infinite

(PHP 4 >= 4.2.0, PHP 5)

is_infinite — 값이 무한인지 확인

설명

bool is_infinite ( float $val )

val가 무한이면(양이던 음이던) TRUE를 반환합니다. log(0)의 결과처럼, 현재 플랫폼의 float에 들어갈 수 없는 너무 큰 값은 무한입니다.

인수

val: 확인할 값

반환값

val이 무한이면 TRUE, 아니면 FALSE.

참고

is_finite() - 값이 허용되는 유한수인지 확인
is_nan() - 값이 수가 아닌지 확인합니다

is_nan

is_finite

[edit] Last updated: Sat, 07 Jan 2012

add a note User Contributed Notes is_infinite

Anonymous 02-May-2012 04:55


PHP_INT_MAX is The largest integer supported in this build of PHP. Usually int(2147483647). Available since PHP 4.4.0 and PHP 5.0.5

stangelanda at arrowquick dot com 28-Aug-2007 07:29


Actually any string ending in INF is more appropriate than any string beginning with INF.  Since negative infinity evaluates to "-INF" but it is still infinite.  However in either case the STRING "INF" is not infinite, only a float that converts to "INF" or "-INF" is infinite.



A more appropriate function might be:

<?php

if (!is_defined('is_infinite')) { function is_infinite($val) {

    return (is_float($val) and ("$val"=='INF' or "$val"=='-INF'));

} }

?>

* However the above function is untested.

21-Aug-2006 08:54


@ david,



That will return true for any string ending with "INF".

I think substr("$value",0,3) would be more appropriate.

david(@t)nirvanis(d@t)org 31-Aug-2004 02:49


If you have PHP lower than 4.2 you can simulate the behaviour:



function is_infinite($value) {

   return (substr("$value",-3) == "INF");

}



(tested on php 4.1.2)

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