is_finite
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
is_infinite
(PHP 4 >= 4.2.0, PHP 5)
is_infinite — 値が無限大であるかどうかを判定する
説明
bool is_infinite
( float
$val
)
val が（正または負の）無限大である場合に
TRUE を返します。たとえば log(0) の結果、
あるいはこのプラットフォーム上で扱える float の範囲を超えた数などが
あてはまります。
パラメータ
-
val -
調べる値。
返り値
val が無限大である場合に TRUE、
そうでない場合に FALSE を返します。
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User Contributed Notes
is_infinite
Anonymous
02-May-2012 04:55
stangelanda at arrowquick dot com
28-Aug-2007 07:29
Actually any string ending in INF is more appropriate than any string beginning with INF. Since negative infinity evaluates to "-INF" but it is still infinite. However in either case the STRING "INF" is not infinite, only a float that converts to "INF" or "-INF" is infinite.
A more appropriate function might be:
<?php
if (!is_defined('is_infinite')) { function is_infinite($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)