PHP 8.5.0 Alpha 1 available for testing

is_numeric

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

is_numeric Determina si una variable es un número o una cadena numérica

Descripción

is_numeric(mixed $value): bool

Determina si la variable dada es un número o una cadena numérica.

Parámetros

value

La variable a evaluar.

Valores devueltos

Retorna true si value es un número o una cadena numérica, false en caso contrario.

Historial de cambios

Versión Descripción
8.0.0 Las cadenas numéricas que terminan con caracteres de espaciado en blanco ("42 ") retornarán ahora true. Anteriormente, se retornaba false en su lugar.

Ejemplos

Ejemplo #1 Ejemplo con 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($element, true) . " es numérico", PHP_EOL;
} else {
echo
var_export($element, true) . " NO es numérico", PHP_EOL;
}
}
?>

El resultado del ejemplo sería:

'42' es numérico
1337 es numérico
1337 es numérico
1337 es numérico
1337 es numérico
1337.0 es numérico
'0x539' NO es numérico
'02471' es numérico
'0b10100111001' NO es numérico
'1337e0' es numérico
'not numeric' NO es numérico
array (
) NO es numérico
9.1 es numérico
NULL NO es numérico
'' NO es numérico

Ejemplo #2 is_numeric() con caracteres de espaciado en blanco

<?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($element, true) . " is numeric", PHP_EOL;
} else {
echo
var_export($element, true) . " is NOT numeric", PHP_EOL;
}
}
?>

Salida del ejemplo anterior en PHP 8:

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

Salida del ejemplo anterior en PHP 7:

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

Ver también

add a note

User Contributed Notes 7 notes

up
95
sobolanx at gmail dot com
14 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
40
tanguy_barsik at hotmail dot com
8 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
13
moskalyuk at gmail dot com
18 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
10
ben at chico dot com
11 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
6
kouber at saparev dot com
21 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
4
Magnus Deininger, dma05 at web dot de
16 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.
up
-2
Katrina Kizenbach
2 years ago
Note that is_numeric() will evaluate to false for number strings using decimal commas.

is_numeric('0.11');
Output: true

is_numeric('0,11');
Output: false
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