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

is_infiniteEncuentra si un valor es infinito


bool is_infinite ( float $val )

Devuelve TRUE si val es infinito (positivo o negativo), como el resultado de log(0) o cualquier valor demasiado grande para caber en un flotante en esta plataforma.



El valor a chequear

Valores devueltos

TRUE si val es infinito, FALSE de lo contrario.

Ver también

  • is_finite() - Encuentra si un valor es un número finito legal
  • is_nan() - Encuentra si un valor no es un número

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User Contributed Notes 5 notes

13 years ago
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)
stangelanda at arrowquick dot com
10 years ago
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:
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.
11 years ago
@ david,

That will return true for any string ending with "INF".
I think substr("$value",0,3) would be more appropriate.
espertalhao04 at hotmail dot com
4 years ago
fastest version to php <4.2:
<?php function is_infinite($v){$v=$v>>0;return -9e1000==$v||$v==9e1000;}; ?>

the $v=$v>>0; is just to ensure it is a number and its not mandatory.
effectively, the function can be reduced to:
<?php function is_infinite($v){return -9e1000==$v||$v==9e1000;}; ?>

this works because any number that is too big or too small for a float is considered to be infinite or -infinite.
5 years ago
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
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