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.
is_infinite
(PHP 4 >= 4.2.0, PHP 5)
is_infinite — Finds whether a value is infinite
Description
bool is_infinite ( float $val )
Returns TRUE if val is infinite (positive or negative), like the result of log(0) or any value too big to fit into a float on this platform.
Parameters
- val
-
The value to check
Return Values
TRUE if val is infinite, else FALSE.
See Also
- is_finite() - Finds whether a value is a legal finite number
- is_nan() - Finds whether a value is not a number
User Contributed Notes
is_infinite
is_infinite
stangelanda at arrowquick dot com
28-Aug-2007 02:29
28-Aug-2007 02:29
21-Aug-2006 03:54
@ david,
That will return true for any string ending with "INF".
I think substr("$value",0,3) would be more appropriate.
david(@t)nirvanis(d@t)org
31-Aug-2004 09:49
31-Aug-2004 09:49
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)