is_float
If you're concerned with speed, you can save yourself about 50% of the time it takes to check whether or not something is an integer pretty easily...
Running through 10,000 iterations of each of the following 3 methods outputs fairly consistently...
<?php
$foo = is_int($i);
// 0.0032429695129395 seconds
$foo = ((int) $i) == $i;
// 0.0020270347595215 seconds
$foo = ((int) $i) === $i;
// 0.001600980758667 seconds
?>
So if you want the best performance and know you're not going to be passed a string that needs to be typed as an integer, use === to compare the type as well.
is_int
(PHP 4, PHP 5)
is_int — Find whether the type of a variable is integer
Description
Finds whether the type of the given variable is integer.
Note: To test if a variable is a number or a numeric string (such as form input, which is always a string), you must use is_numeric().
Parameters
- var
-
The variable being evaluated.
Return Values
Returns TRUE if var is an integer, FALSE otherwise.
Examples
Example #1 is_int() example
<?php
if (is_int(23)) {
echo "is integer\n";
} else {
echo "is not an integer\n";
}
var_dump(is_int(23));
var_dump(is_int("23"));
var_dump(is_int(23.5));
var_dump(is_int(true));
?>
The above example will output:
is integer bool(true) bool(false) bool(false) bool(false)
See Also
- is_bool() - Finds out whether a variable is a boolean
- is_float() - Finds whether the type of a variable is float
- is_numeric() - Finds whether a variable is a number or a numeric string
- is_string() - Find whether the type of a variable is string
- is_array() - Finds whether a variable is an array
- is_object() - Finds whether a variable is an object
add a note
User Contributed Notesis_int
corey at effim dot com
09-Jun-2009 08:21
09-Jun-2009 08:21
Anonymous
03-Jun-2009 03:39
03-Jun-2009 03:39
Typecasting will return false if a string has leading zeroes. If you prefer '023' return true, try:
<?php
function really_is_int($val)
{
if(func_num_args() !== 1)
exit(__FUNCTION__.'(): not passed 1 arg');
return ($val !== true) && ((string)abs((int) $val)) === ((string) ltrim($val, '-0'));
}
?>
e dot sand at elisand dot com
09-Apr-2009 03:27
09-Apr-2009 03:27
Simon Neaves was close on explaining why his function is perfect choice for testing for an int (as possibly most people would need). He made some errors on his ctype_digit() output though - possibly a typo, or maybe a bug in his version of PHP at the time.
The correct output for parts of his examples should be:
<?php
var_dump(ctype_digit(23)); //bool(false)
var_dump(ctype_digit("23")); //bool(true)
var_dump(ctype_digit(23.5)); //bool(false)
var_dump(ctype_digit(NULL)); //bool(false)
var_dump(ctype_digit("")); //bool(false)
?>
As you can see, the reason why using *just* ctype_digit() may not always work is because it only returns TRUE when given a string as input - given a number value and it returns FALSE (which may be unexpected).
leonix at motd dot ru
16-Dec-2008 08:08
16-Dec-2008 08:08
another_is_int() is almost perfect, but it treats boolean true as int because
1 == (int) true == (string) true == '1'.
Fixed version:
<?php
/**
* Checks if the given value represents integer
*/
function int_ok($val)
{
return ($val !== true) && ((string)(int) $val) === ((string) $val);
}
?>
paulo dot koch at g_mail dot com
17-Oct-2008 07:30
17-Oct-2008 07:30
Don't over-engineer it.
<?php
function another_is_int($a){
return ((string) $a) === ((string)(int) $a);
}
?>
Wryel Covo - ryryel[at]gmail[dot]com
14-Oct-2008 06:53
14-Oct-2008 06:53
<?php
function onlyNumbers($string){
//This function removes all characters other than numbers
//Esta função limpa a url e conserva apenas os numeros
$string = preg_replace("/[^0-9]/", "", $string);
return (int) $string;
}
echo $test = onlyNumbers("as87d68a6db8a7d686dx8a6dx"); //2147483647
echo "<br/>";
echo onlyNumbers("xn89d9x797d9a8x7-"); //899797987
echo "<br/>";
if(is_int($test)){
echo "Is int ! - É inteiro !"; // This OK !
} else {
echo "Not int ! - Não é inteiro";
}
?>
mark at codedesigner dot nl
26-Jun-2008 01:34
26-Jun-2008 01:34
updated version from Simon Neaves
<?php
function isInteger($input){
return preg_match('@^[-]?[0-9]+$@',$input) === 1;
}
?>
this function checks if the string:
- starts with a - sign (optional)
- ends with 1 or more numeric chars
Julien Picalausa
11-May-2008 09:44
11-May-2008 09:44
To check if a string ($s) is a representation of an integer (including representations is scientific notation and negative numbers), you can use the following test, provided that you don't expect values that are out of bounds for an integer.
is_numeric($s) && floatval($s) == intval(floatval($s))
If the test returns true, the string is a representation of an integer.
is_numeric (if it works as intended) protects from strings that are not proper numbers.
The comparison filters anything that is non_integer
If, for performance reasons, you want to avoid converting to float twice, it can also be written:
is_numeric($s) && ($f = floatval($s)) == intval($f)
If you plan to get values that cannot be representated with an integer and are ready to deal with a float, you can use floor instead of intval, as long as you are ready to deal with floats. Even so, that method will become unreliable when the precision of the float becomes insufficient for getting to the fractional part of the number
Simon Neaves
29-Apr-2008 06:14
29-Apr-2008 06:14
I've found that both that is_int and ctype_digit don't behave quite as I'd expect, so I made a simple function called isInteger which does. I hope somebody finds it useful.
<?php
function isInteger($input){
return(ctype_digit(strval($input)));
}
var_dump(is_int(23)); //bool(true)
var_dump(is_int("23")); //bool(false)
var_dump(is_int(23.5)); //bool(false)
var_dump(is_int(NULL)); //bool(false)
var_dump(is_int("")); //bool(false)
var_dump(ctype_digit(23)); //bool(true)
var_dump(ctype_digit("23")); //bool(false)
var_dump(ctype_digit(23.5)); //bool(false)
var_dump(ctype_digit(NULL)); //bool(false)
var_dump(ctype_digit("")); //bool(true)
var_dump(isInteger(23)); //bool(true)
var_dump(isInteger("23")); //bool(true)
var_dump(isInteger(23.5)); //bool(false)
var_dump(isInteger(NULL)); //bool(false)
var_dump(isInteger("")); //bool(false)
?>
qlimmax at gmail dot com
07-Apr-2008 05:58
07-Apr-2008 05:58
function is_natural($natural,$zero=true)
{
if(ctype_digit($natural))
{
if($zero)
{
$natural_test=(int)$natural;
if((string)$natural_test !== $natural) return false;
else return true;
}
else return true;
}
else return false;
}
true for ("0","1","2","3",...) false for("-1","01","adS","#@!$%^&*-...","0.7","0,7", "0x12",...)
if $zero=false
true for("0","00","1","01",...) false("-1","#@!$%^&*-...","adS","0.7","0,7", "0x12",...)
wes9999 a myfastmail com
30-Nov-2007 05:28
30-Nov-2007 05:28
a small modification to the isInt checks provided by lclkk at urbanvagabond dot net to make them work for scientific notation integers that are provided in string form:
function myIsInt ($x) {
return (is_numeric($x) ? intval($x+0) == $x : false);
}
function Test($x) {
echo "$x is " . ( myIsInt($x) ? ('an integer. The integer value is ' . intval($x+0)) : 'not an integer.');
echo "\n";
}
Note the additional adding of 0 to $x in both functions.
This would allow the following tests to return true:
Test('53.45e2'); // 5345
Test('53.45e3'); // 53450
and this one to return false:
Test('53.45e1'); // 534.5
tudor at tudorholton dot com
05-Jul-2007 01:27
05-Jul-2007 01:27
Please note this from the Integer datatype page:
"The size of an integer is platform-dependent, although a maximum value of about two billion is the usual value (that's 32 bits signed). PHP does not support unsigned integers. Integer size can be determined from PHP_INT_SIZE, maximum value from PHP_INT_MAX since PHP 4.4.0 and PHP 5.0.5."
This is particularly important if you are doing validation of large keys or any number larger than 2,000,000,000 (e.g. telephone numbers)
Ender at soldat dot nl
16-Feb-2006 11:38
16-Feb-2006 11:38
Be aware that is_numeric (mentioned in this article as the proper way to validate string numbers) also allows numbers in scientific and hexadecimal annotation. Thus DO NOT USE that function to validate user input that will be used as id number for in a query for example, this could cause mysql errors. Use ctype_digit instead.
ludvig dot ericson at gmail dot com
06-Jan-2006 09:00
06-Jan-2006 09:00
I would like to say that is_int() is pretty helpfull when looking for neat proper ways to check functions that return either integers or booleans (false) on failure (strpos, socket_select, etc.)
<?php
function mySelect() {
global $someSockets;
$ret = socket_select($someSockets, $o = array(), $e = array(), 0);
if (!$ret)
return is_int($ret);
/* FURTHER PROCESSING HERE */
return true; // Return true if the function proceeded as expected.
}
?>
The point of doing this is that if you put this in a while() loopo, you'll break it when the select fails.
<?php
while (mySelect());
?>
Hope you get the point
- toxik
lclkk at urbanvagabond dot net
16-Sep-2003 02:24
16-Sep-2003 02:24
I think the function below is a robust test for integers working on all datatypes. It works by first checking that a number can be evaluated numerically, and then secondly that the integer evaluation matches the original number.
Test cases are included.
<?
function myIsInt ($x) {
return (is_numeric($x) ? intval($x) == $x : false);
}
function Test($x) {
echo "$x is " . ( myIsInt($x) ? ('an integer. The integer value is ' . intval($x)) : 'not an integer.');
echo "\n";
}
echo "These should be integers...\n";
Test(1);
Test(5);
Test(10);
Test(10.0);
Test(20.0);
Test(-20.0);
Test(0+4+4.5+4.5);
Test("10.0");
Test("+14");
Test("-15");
Test("0");
echo "\nThese should not be integers...\n";
Test(true); // watch out, this displays as '1'
Test(false);
Test("moose");
Test("3.5");
Test("-214235.5");
Test(""); // empty string
Test(array(1,2,3));
Test(dir('.')); // object
Test(null);
?>
gabe at websaviour dot com
14-Jul-2003 06:08
14-Jul-2003 06:08
Although this can be inferred from the documentation, beware of numeric strings. I ran into the problem in a MySQL app where I would either SELECT an INT PRIMARY KEY or INSERT a new record and use mysql_insert_id() to get the KEY before continuing onto the new section.
I used is_int() to make sure the subsequent queries wouldn't break when using the key variable. Unfortunately I failed to realize that while mysql_insert_id() returns an int, mysql_result() always returns a string even if you are SELECTing from an INT field.
Spent at least 30 minutes trying to figure out why existing records weren't getting linked, but new records would link fine. I ended up using intval() on mysql_result() to make sure subsequent queries still always work.
phpguru at gmx dot ch
05-Jul-2003 03:50
05-Jul-2003 03:50
To Logan:
There's also a simple non-regexp way to convert a (form) value into an integer if it consists of numbers only - although with a trap (see below):
if ($_POST["number"] == (int)$_POST["number"]) $_POST["number"] = (int)$_POST["number"];
The "traps" (or "side effects") appear with values like "" (empty string) and false (boolean), which are converted to 0 (integer). But in certain cases this might be desirable or/and usefull ;-)
Solutions like
if (($_POST["number"] + 1 - 1) == $_POST["number"]) ...
falls into the same category.
mark at g33kz dot co dot uk
18-Jun-2003 12:44
18-Jun-2003 12:44
Or you could just use is_numeric()
I have a file called input.php which I run at the beginning of all my scripts which makes sure all my input numbers are converted to integers automatically.
if ($_GET) {
foreach ($_GET as $k => $v) {
$_GET[$k] = trim (stripslashes ($v));
if (is_numeric ($v)) {
$_GET[$k] = intval ($v);
}
}
}
if ($_POST) {
foreach ($_POST as $k => $v) {
$_POST[$k] = trim (stripslashes ($v));
if (is_numeric ($v)) {
$_POST[$k] = intval ($v);
}
}
}
if ($_COOKIE) {
foreach ($_COOKIE as $k => $v) {
$_COOKIE[$k] = trim (stripslashes ($v));
if (is_numeric ($v)) {
$_COOKIE[$k] = intval ($v);
}
}
}
logan at logannet dot net
10-Feb-2003 11:42
10-Feb-2003 11:42
[[Editors note: Or you can simply use is_numeric()]]
Some people have offered their ways to find out if a string from a form is an integer or not, here's my way:
if(ereg("^[0-9]+$", $_POST["number"])) $_POST["number"] = (int)$_POST["number"];
In psuedo code:
if you are a string full of numbers then convert yourself to an integer
So instead of just checking if its a string full of numbers you check and then convert it, which means you can use the standard is_int. You can also do:
if(ereg("^[0-9]+$", $_POST["number"])) $_POST["number"] += 0;
I think the first way i mentioned is better because your coding what you want to do, rather than the second way that uses a side effect of adding 0 to convert the string.
The first way also may make your code ever so slightly faster (nothing noticeable) as php does not need to add 0 to the number after it converts it.
Also note an integer is full numbers (1, 2, 3 etc) not decimal numbers (1.1, 2.4, 3.7 etc), to convert decimal numbers you could use something like:
if(ereg("^[.0-9]+$", $_POST["number"])) $_POST["number"] = (float)$_POST["number"];
OR
if(ereg("^[.0-9]+$", $_POST["number"])) $_POST["number"] += 0;
But note that these would not work with is_int(), because they are not integers.