is_infinite
For seeing whether or not something is a number, use ctype_digit().
is_nan
(PHP 4 >= 4.2.0, PHP 5)
is_nan — Indique si une valeur n'est pas un nombre
Description
bool is_nan
( float $val
)
Vérifie si val est 'not a number' (pas un nombre), comme le résultat de acos(1.01).
Liste de paramètres
- val
-
La valeur à vérifier
Valeurs de retour
Retourne TRUE si val est 'not a number' (pas un nombre), sinon, FALSE.
Exemples
Exemple #1 Exemple avec is_nan()
<?php
// Calcul invalide, doit retourner une
// valeur NaN
$nan = acos(8);
var_dump($nan, is_nan($nan));
?>
L'exemple ci-dessus va afficher :
float(NAN) bool(true)
Voir aussi
- is_finite() - Indique si un nombre est fini
- is_infinite() - Indique si un nombre est infini
add a note
User Contributed Notesis_nan
darkangel at moveinmod dot net
02-Mar-2006 06:04
02-Mar-2006 06:04
nan/"not a number" is not meant to see if the data type is numeric/textual/etc..
NaN is actually a set of values which can be stored in floating-point variables, but dont actually evaluate to a proper floating point number.
The floating point system has three sections: 1 bit for the sign (+/-), an 8 bit exponent, and a 23 bit fractional part.
There are rules governing which combinations of values can be placed into each section, and some values are reserved for numbers such as infinity. This leads to certain combinations being invalid, or in other words, not a number.
Sku
04-Dec-2005 09:29
04-Dec-2005 09:29
Hi nez,
better would be:
function isNaN( $var ) {
return !ereg ("^[-]?[0-9]+([\.][0-9]+)?$", $var);
}
ys, Sku
nez [at] NOSPAM gazeta [dot] pl
26-Sep-2005 08:27
26-Sep-2005 08:27
Paul, i guess better would be:
function isNaN( $var ) {
return ereg ("^[-]?[0-9]+([\.][0-9]+)?$", $var);
}
Vincent
24-Feb-2005 02:04
24-Feb-2005 02:04
Since NaN is not even equal to itself, here is a way to test it:
<?php
function my_is_nan($_) {
return ($_ !== $_);
}
?>