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is_float

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

is_floatDétermine si une variable est de type nombre décimal

Description

is_float(mixed $value): bool

Détermine si la variable donnée est de type nombre décimal.

Note:

Pour tester si une variable est un nombre ou une chaîne numérique (comme les entrées de formulaire, qui sont toujours des chaînes), vous devez utiliser la fonction is_numeric().

Liste de paramètres

value

La variable à évaluer.

Valeurs de retour

Retourne true si value est un nombre décimal, false sinon.

Exemples

Exemple #1 Exemple avec is_float()

<?php

var_dump
(is_float(27.25));
var_dump(is_float('abc'));
var_dump(is_float(23));
var_dump(is_float(23.5));
var_dump(is_float(1e7)); //Notation Scientifique
var_dump(is_float(true));
?>

L'exemple ci-dessus va afficher :

bool(true)
bool(false)
bool(false)
bool(true)
bool(true)
bool(false)

Voir aussi

  • is_bool() - Détermine si une variable est un booléen
  • is_int() - Détermine si une variable est de type nombre entier
  • is_numeric() - Détermine si une variable est un nombre ou une chaîne numérique
  • is_string() - Détermine si une variable est de type chaîne de caractères
  • is_array() - Détermine si une variable est un tableau
  • is_object() - Détermine si une variable est de type objet

add a note

User Contributed Notes 6 notes

up
21
nonzer0value
9 years ago
Coercing the value to float and back to string was a neat trick. You can also just add a literal 0 to whatever you're checking.

<?php
function isfloat($value) {
// PHP automagically tries to coerce $value to a number
return is_float($value + 0);
}
?>

Seems to work ok:

<?php
isfloat
("5.0" + 0); // true
isfloat("5.0"); // false
isfloat(5 + 0); // false
isfloat(5.0 + 0); // false
isfloat('a' + 0); // false
?>

YMMV
up
21
Boylett
15 years ago
If you want to test whether a string is containing a float, rather than if a variable is a float, you can use this simple little function:

function isfloat($f) return ($f == (string)(float)$f);
up
4
Anonymous
3 years ago
is_float() returns true for NAN, INF and -INF. You may want to test is_float($value) && is_finite($value), or alternatively filter_var($value, FILTER_VALIDATE_FLOAT) !== false.
up
7
kshegunov at gmail dot com
16 years ago
As celelibi at gmail dot com stated, is_float checks ONLY the type of the variable not the data it holds!

If you want to check if string represent a floating point value use the following regular expression and not is_float(),
or poorly written custom functions.

/^[+-]?(([0-9]+)|([0-9]*\.[0-9]+|[0-9]+\.[0-9]*)|
(([0-9]+|([0-9]*\.[0-9]+|[0-9]+\.[0-9]*))[eE][+-]?[0-9]+))$/
up
6
Erutan409 at Hotmail dot com
9 years ago
Boylett's solution is elegant (http://php.net/manual/en/function.is-float.php#85848), but won't work for long float's or variables that are not explicitly type of 'string' or for long floats that are encased in quotes, making it a string that will be truncated/rounded when cast to a float. So, further logic must be completed to test for the case. Take the following example:

<?php

if (!function_exists("test_float")) {

function
test_float($test) {

if (!
is_scalar($test)) {return false;}

$type = gettype($test);

if (
$type === "float") {
return
true;
} else {
return
preg_match("/^\\d+\\.\\d+$/", $test) === 1;
}

}

}

$test = "3.14159265358979323846264338g32795";

var_dump($test);
var_dump((float)$test);
var_dump($test == (string)(float)$test);
var_dump(test_float($test));

?>

Will produce (32-bit):

string(34) "3.14159265358979323846264338g32795"
float(3.1415926535898)
bool(false)
bool(false)

So far, so good, right? Yeah, but it's misleading, because the string is so long, that when it's converted to a float, it won't be equivalent to the comparison of the value being cast back into a string . So the aforementioned short function works. Look at this next example:

<?php

$test
= 3.1415926535897932384626433832795;

var_dump($test);
var_dump((float)$test);
var_dump($test == (string)(float)$test);
var_dump(test_float($test));

?>

Will produce (32-bit):

float(3.1415926535898)
float(3.1415926535898)
bool(false)
bool(true)

Why is it not working now, but the value is truly a float? Same reasoning as mentioned before. The float is so long that it's truncated/rounded and doesn't match the comparison being done with the short-hand function.

So, as you can see, more logic should be applied to the variable you're testing.
up
6
KIVagant at gmail dot com
11 years ago
Yet another regular expression for float in real life:

<?php
function isTrueFloat($val)
{
$pattern = '/^[-+]?(((\\\\d+)\\\\.?(\\\\d+)?)|\\\\.\\\\d+)([eE]?[+-]?\\\\d+)?$/';

return (!
is_bool($val) && (is_float($val) || preg_match($pattern, trim($val))));
}
?>

// Matches:
1, -1, 1.0, -1.0, '1', '-1', '1.0', '-1.0', '2.1', '0', 0, ' 0 ', ' 0.1 ', ' -0.0 ', -0.0, 3., '-3.', '.27', .27, '-0', '+4', '1e2', '+1353.0316547', '13213.032468e-13465', '-8E+3', '-1354.98879e+37436'

// Non-matches:
false, true, '', '-', '.a', '-1.a', '.a', '.', '-.', '1+', '1.3+', 'a1', 'e.e', '-e-4', 'e2', '8e', '3,25'
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