(PHP 4, PHP 5)
is_int — 检测变量是否是整数
如果 var 是 integer 则返回 TRUE，否则返回 FALSE。
Note:
若想测试一个变量是否是数字或数字字符串（如表单输入，它们通常为字符串），必须使用 is_numeric()。
参见 is_bool()、 is_float()、 is_integer()、 is_numeric()、 is_string()、 is_array() 和 is_object()。
some at somewhere dot com (2013-07-02 03:35:10)
<?php
// check if input is a valid number
// first number must be 1 thru 9, followed by a number 0-9, no decimals
// true for "1", "1000"
// false for "01", "-1", "1.2"
function isInteger($input){
return preg_match('@^[1-9][0-9]*$@',$input) === 1;
}
?>
petepostma at gmail dot spam dot com (2012-07-17 18:38:40)
There is a versa to the vice of this int only type check.
is_int( $integer_type) will only return true, if the TYPE is int, not the value
ctype_digit( $string_type) will only return true if the TYPE is string, and its value is INT
therefore:
return ( is_int($value) || ctype_digit($value) );
nicolas dot giraud at actiane dot com (2012-06-27 09:24:07)
Just a shorter way to check if your variable is an int or a string containing a int without others digit than 0 to 9 :
<?php
$bool = ( !is_int($value) ? (ctype_digit($value)) : true );
$value = 42; //true
$value = '42'; //true
$value = '1e9'; //false
$value = '0155'; //true
$value = 0155; //true
$value = 0xFF; //true while it's just the same as 255
$value = '0xFF'; //false
$value = 'a'; //false
$value = array(); //false
$value = array('5'); //false
$value = array(5); false
$value = ''; //false
$value = NULL; //false
?>
Short & cool :)
arturs at indigo dot lv (2012-05-04 11:31:21)
Sometime needed check if string containing numbers is integer or not. Then I created this small function:
<?php
function is_integer2($v) {
$i = intval($v);
if ("$i" == "$v") {
return TRUE;
} else {
return FALSE;
}
}
?>
andre dot roesti at 7flex dot net (2010-07-27 05:51:07)
With this function you can check if every of multiple variables are int. This is a little more comfortable than writing 'is_int' for every variable you've got.
<?php
function are_int ( ) {
$args = func_get_args ();
foreach ( $args as $arg )
if ( ! is_int ( $arg ) )
return false;
return true;
}
// Example:
are_int ( 4, 9 ); // true
are_int ( 22, 08, 'foo' ); // false
?>
Robin (2010-03-27 08:22:04)
Keep in mind that is_int() operates in signed fashion, not unsigned, and is limited to the word size of the environment php is running in.
In a 32-bit environment:
<?php
is_int( 2147483647 ); // true
is_int( 2147483648 ); // false
is_int( 9223372036854775807 ); // false
is_int( 9223372036854775808 ); // false
?>
In a 64-bit environment:
<?php
is_int( 2147483647 ); // true
is_int( 2147483648 ); // true
is_int( 9223372036854775807 ); // true
is_int( 9223372036854775808 ); // false
?>
If you find yourself deployed in a 32-bit environment where you are required to deal with numeric confirmation of integers (and integers only) potentially breaching the 32-bit span, you can combine is_int() with is_float() to guarantee a cover of the full, signed 64-bit span:
<?php
$small = 2147483647; // will always be true for is_int(), but never for is_float()
$big = 9223372036854775807; // will only be true for is_int() in a 64-bit environment
if( is_int($small) || is_float($small) ); // passes in a 32-bit environment
if( is_int($big) || is_float($big) ); // passes in a 32-bit environment
?>
thierryreeuwijk at hotmail dot com (2010-01-14 02:04:26)
If you only want integer values like 23 or 0155, or form/string integer values like "23" or "0155" to be valid, this should work just fine.
<?php
function int($int){
// First check if it's a numeric value as either a string or number
if(is_numeric($int) === TRUE){
// It's a number, but it has to be an integer
if((int)$int == $int){
return TRUE;
// It's a number, but not an integer, so we fail
}else{
return FALSE;
}
// Not a number
}else{
return FALSE;
}
}
print("155".int(155)."<br>");
print("15.5".int(15.5)."<br>");
print("\"155\"".int("155")."<br>");
print("\"15.5\"".int("15.5")."<br>");
print("\"0155\"".int("0155")."<br>");
print("\"I'm 155\"".int("I'm 155")."<br>");
print("\"test\"".int("test")."<br>");
print("\"\"".int(""));
?>
The above returns:
155 TRUE
15.5 FALSE
"155" TRUE
"15.5" FALSE
"0155" TRUE
"I'm 155" FALSE
"test" FALSE
"" FALSE
me at rexxars dot com (2009-09-16 05:23:02)
I was looking for the fastest way to check for an unsigned integer which supported large numbers like 4318943448871348 or 0xFFFFFFFF.
Fastest I came up with is this:
<?php
function is_unsigned_int($val) {
return ctype_digit((string) $value));
}
?>
Will return true on 1515, 0xFFFFFFFF, '3515' and '1365158185855141'.
Will return false on 0.1515, '415.4134' and '-616'.
Be aware though, before PHP 5.1.0 this will return true on an empty string.
According to my benchmarks this is about 30% faster than the regex ^\d+$.
Roberto Rama (2009-07-21 11:39:40)
Use this instead if you wanna know if a string is explicitly a number:
<?php
function isint( $mixed )
{
return ( preg_match( '/^\d*$/' , $mixed) == 1 );
}
var_export( isint( '123' ) ); //This will return true
var_export( isint( 123 ) ); //This will return true
var_export( isint( 'asd' ) ); //This will return false
var_export( isint( '123asd123' ) ); //This will return false
?>
corey at effim dot com (2009-06-09 13:21:50)
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) === $i;
// 0.001600980758667 seconds
?>
So if you want the best performance and know you're not going to be passed a string that needs to be typed as an integer, use === to compare the type as well.
Anonymous (2009-06-03 08:39:55)
Typecasting will return false if a string has leading zeroes. If you prefer '023' return true, try:
<?php
function really_is_int($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 (2009-04-09 08:27:26)
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 (2008-12-16 00:08:23)
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) $val);
}
?>
paulo dot koch at g_mail dot com (2008-10-17 12:30:19)
Don't over-engineer it.
<?php
function another_is_int($a){
return ((string) $a) === ((string)(int) $a);
}
?>
Wryel Covo - ryryel[at]gmail[dot]com (2008-10-14 11:53:12)
<?php
function onlyNumbers($string){
//This function removes all characters other than numbers
//Esta fun??o 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 ! - ? inteiro !"; // This OK !
} else {
echo "Not int ! - N?o é inteiro";
}
?>
mark at codedesigner dot nl (2008-06-26 06:34:29)
updated version from Simon Neaves
<?php
function isInteger($input){
return preg_match('@^[-]?[0-9]+$@',$input) === 1;
}
?>
this function checks if the string:
- starts with a - sign (optional)
- ends with 1 or more numeric chars
Julien Picalausa (2008-05-11 02:44:12)
To check if a string ($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($f)
If you plan to get values that cannot be representated with an integer and are ready to deal with a float, you can use floor instead of intval, as long as you are ready to deal with floats. Even so, that method will become unreliable when the precision of the float becomes insufficient for getting to the fractional part of the number
Simon Neaves (2008-04-29 11:14:08)
I've found that both that is_int and ctype_digit don't behave quite as I'd expect, so I made a simple function called isInteger which does. I hope somebody finds it useful.
<?php
function isInteger($input){
return(ctype_digit(strval($input)));
}
var_dump(is_int(23)); //bool(true)
var_dump(is_int("23")); //bool(false)
var_dump(is_int(23.5)); //bool(false)
var_dump(is_int(NULL)); //bool(false)
var_dump(is_int("")); //bool(false)
var_dump(ctype_digit(23)); //bool(true)
var_dump(ctype_digit("23")); //bool(false)
var_dump(ctype_digit(23.5)); //bool(false)
var_dump(ctype_digit(NULL)); //bool(false)
var_dump(ctype_digit("")); //bool(true)
var_dump(isInteger(23)); //bool(true)
var_dump(isInteger("23")); //bool(true)
var_dump(isInteger(23.5)); //bool(false)
var_dump(isInteger(NULL)); //bool(false)
var_dump(isInteger("")); //bool(false)
?>
qlimmax at gmail dot com (2008-04-07 10:58:02)
function is_natural($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 (2007-11-30 09:28:22)
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 (2007-07-04 18:27:59)
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 (2006-02-16 03:38:29)
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 (2006-01-06 13:00:41)
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($ret);
/* FURTHER PROCESSING HERE */
return true; // Return true if the function proceeded as expected.
}
?>
The point of doing this is that if you put this in a while() loopo, you'll break it when the select fails.
<?php
while (mySelect());
?>
Hope you get the point
- toxik
lclkk at urbanvagabond dot net (2003-09-15 19:24:49)
I think the function below is a robust test for integers working on all datatypes. It works by first checking that a number can be evaluated numerically, and then secondly that the integer evaluation matches the original number.
Test cases are included.
<?
function myIsInt ($x) {
return (is_numeric($x) ? intval($x) == $x : false);
}
function Test($x) {
echo "$x is " . ( myIsInt($x) ? ('an integer. The integer value is ' . intval($x)) : 'not an integer.');
echo "\n";
}
echo "These should be integers...\n";
Test(1);
Test(5);
Test(10);
Test(10.0);
Test(20.0);
Test(-20.0);
Test(0+4+4.5+4.5);
Test("10.0");
Test("+14");
Test("-15");
Test("0");
echo "\nThese should not be integers...\n";
Test(true); // watch out, this displays as '1'
Test(false);
Test("moose");
Test("3.5");
Test("-214235.5");
Test(""); // empty string
Test(array(1,2,3));
Test(dir('.')); // object
Test(null);
?>
gabe at websaviour dot com (2003-07-14 11:08:41)
Although this can be inferred from the documentation, beware of numeric strings. I ran into the problem in a MySQL app where I would either SELECT an INT PRIMARY KEY or INSERT a new record and use mysql_insert_id() to get the KEY before continuing onto the new section.
I used is_int() to make sure the subsequent queries wouldn't break when using the key variable. Unfortunately I failed to realize that while mysql_insert_id() returns an int, mysql_result() always returns a string even if you are SELECTing from an INT field.
Spent at least 30 minutes trying to figure out why existing records weren't getting linked, but new records would link fine. I ended up using intval() on mysql_result() to make sure subsequent queries still always work.
logan at logannet dot net (2003-02-10 15:42:32)
[[Editors note: Or you can simply use is_numeric()]]
Some people have offered their ways to find out if a string from a form is an integer or not, here's my way:
if(ereg("^[0-9]+$", $_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.