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 ejemplo anterior mostrará :

'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;
    }
}
?>

Resultado del ejemplo anterior en PHP 8 :

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

Resultado del ejemplo anterior en PHP 7 :

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

Ver también

Las cadenas numéricas
ctype_digit() - Chequear posibles caracteres numéricos
is_bool() - Determina si una variable es un bool
is_null() - Indica si una variable es null
is_float() - Determina si una variable es de tipo float
is_int() - Determina si una variable es de tipo integer
is_string() - Determina si una variable es de tipo string
is_object() - Determina si una variable es de tipo objeto
is_array() - Determina si una variable es un array
filter_var() - Filtra una variable con el filtro que se indique

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User Contributed Notes 7 notes

down

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.

down

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

down

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

down

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...

down

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);
}

down

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.

down

-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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