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is_numeric

(PHP 4, PHP 5, PHP 7, PHP 8)

is_numeric Détermine si une variable est un nombre ou une chaîne numérique

Description

is_numeric(mixed $value): bool

Détermine si la variable donnée est un nombre ou une chaîne numérique.

Liste de paramètres

value

La variable à évaluer.

Valeurs de retour

Retourne true si value est un nombre ou une chaîne numérique, false sinon.

Historique

Version Description
8.0.0 Les chaînes numériques terminant avec des caractères d'espacement blanc ("42 ") retourneront désormais true. Auparavant, false était retourné à la place.

Exemples

Exemple #1 Exemple avec is_numeric()

<?php
$tests 
= array(
    
"42",
    
1337,
    
0x539,
    
02471,
    
0b10100111001,
    
1337e0,
    
"0x539",
    
"02471",
    
"0b10100111001",
    
"1337e0",
    
"not numeric",
    array(),
    
9.1,
    
null,
    
'',
);

foreach (
$tests as $element) {
    if (
is_numeric($element)) {
        echo 
var_export($elementtrue) . " est numérique"PHP_EOL;
    } else {
        echo 
var_export($elementtrue) . " N'est PAS numérique"PHP_EOL;
    }
}
?>

L'exemple ci-dessus va afficher :

'42' est numérique
1337 est numérique
1337 est numérique
1337 est numérique
1337 est numérique
1337.0 est numérique
'0x539' N'est PAS numérique
'02471' est numérique
'0b10100111001' N'est PAS numérique
'1337e0' est numérique
'not numeric' N'est PAS numérique
array (
) N'est PAS numérique
9.1 est numérique
NULL N'est PAS numérique
'' N'est PAS numérique

Exemple #2 is_numeric() avec des caractères d'espacement blanc

<?php
$tests 
= [
    
" 42",
    
"42 ",
    
"\u{A0}9001"// non-breaking space
    
"9001\u{A0}"// non-breaking space
];

foreach (
$tests as $element) {
    if (
is_numeric($element)) {
        echo 
var_export($elementtrue) . " is numeric"PHP_EOL;
    } else {
        echo 
var_export($elementtrue) . " is NOT numeric"PHP_EOL;
    }
}
?>

Résultat de l'exemple ci-dessus en PHP 8 :

' 42' is numeric
'42 ' is numeric
' 9001' is NOT numeric
'9001 ' is NOT numeric

Résultat de l'exemple ci-dessus en PHP 7 :

' 42' is numeric
'42 ' is NOT numeric
' 9001' is NOT numeric
'9001 ' is NOT numeric

Voir aussi

add a note

User Contributed Notes 7 notes

up
82
sobolanx at gmail dot com
11 years ago
Note that the function accepts extremely big numbers and correctly evaluates them.

For example:

<?php
    $v
= is_numeric ('58635272821786587286382824657568871098287278276543219876543') ? true : false;
   
   
var_dump ($v);
?>

The above script will output:

bool(true)

So this function is not intimidated by super-big numbers. I hope this helps someone.

PS: Also note that if you write is_numeric (45thg), this will generate a parse error (since the parameter is not enclosed between apostrophes or double quotes). Keep this in mind when you use this function.
up
31
tanguy_barsik at hotmail dot com
5 years ago
for strings, it return true only if float number has a dot

is_numeric( '42.1' )//true
is_numeric( '42,1' )//false
up
10
moskalyuk at gmail dot com
16 years ago
is_numeric fails on the hex values greater than LONG_MAX, so having a large hex value parsed through is_numeric would result in FALSE being returned even though the value is a valid hex number
up
7
ben at chico dot com
8 years ago
Apparently NAN (Not A Number) is a number for the sake of is_numeric().

<?php
echo "is ";
if (!
is_numeric(NAN))
echo
"not ";
echo
"a number";
?>

Outputs "is a number". So something that is NOT a number (by defintion) is a number...
up
2
kouber at saparev dot com
19 years ago
Note that this function is not appropriate to check if "is_numeric" for very long strings. In fact, everything passed to this function is converted to long and then to a double. Anything greater than approximately 1.8e308 is too large for a double, so it becomes infinity, i.e. FALSE. What that means is that, for each string with more than 308 characters, is_numeric() will return FALSE, even if all chars are digits.

However, this behaviour is platform-specific.

http://www.php.net/manual/en/language.types.float.php

In such a case, it is suitable to use regular expressions:

function is_numeric_big($s=0) {
  return preg_match('/^-?\d+$/', $s);
}
up
0
anantkumarsingh03101988 at gmail dot com
3 months ago
Example #2

Output:

'9001 ' is NOT numeric

is incorrect for PHP8, it's numeric.

So please correct this.
up
0
Magnus Deininger, dma05 at web dot de
13 years ago
regarding the global vs. american numeral notations, it should be noted that at least in japanese, numbers aren't grouped with an extra symbol every three digits, but rather every four digits (for example 1,0000 instead of 10.000). also nadim's regexen are slightly suboptimal at one point having an unescaped '.' operator, and the whole thing could easily be combined into a single regex (speed and all).

adjustments:

<?php
$eng_or_world
= preg_match
 
('/^[+-]?'. // start marker and sign prefix
 
'(((([0-9]+)|([0-9]{1,4}(,[0-9]{3,4})+)))?(\\.[0-9])?([0-9]*)|'. // american
 
'((([0-9]+)|([0-9]{1,4}(\\.[0-9]{3,4})+)))?(,[0-9])?([0-9]*))'. // world
 
'(e[0-9]+)?'. // exponent
 
'$/', // end marker
 
$str) == 1;
?>

i'm sure this still isn't optimal, but it should also cover japanese-style numerals and it fixed a couple of other issues with the other regexen. it also allows for an exponent suffix, the pre-decimal digits are optional and it enforces using either grouped or ungrouped integer parts. should be easier to trim to your liking too.
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