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is_int

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

is_int — 检测变量是否是整数

说明

is_int(mixed $value): bool

检测变量的类型是否为整数（integer）。

注意:
若想检测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），则必须使用 is_numeric() 。

参数

value: 要检测的变量。

返回值

如果 value 是 int，则返回 true，否则返回 false。

示例

示例 #1 is_int() 示例

<?php
$values = array(23, "23", 23.5, "23.5", null, true, false);
foreach ($values as $value) {
    echo "is_int(";
    var_export($value);
    echo ") = ";
    var_dump(is_int($value));
}
?>

以上示例会输出：

 
is_int(23) = bool(true)
is_int('23') = bool(false)
is_int(23.5) = bool(false)
is_int('23.5') = bool(false)
is_int(NULL) = bool(false)
is_int(true) = bool(false)
is_int(false) = bool(false)

参见

is_bool() - 检测变量是否是布尔值
is_float() - 查找变量的类型是否是浮点型
is_numeric() - 检测变量是否为数字或数字字符串
is_string() - 查找变量的类型是否是字符串
is_array() - 检测变量是否是数组
is_object() - 查找变量是否是对象

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User Contributed Notes 30 notes

down

168

Simon Neaves ¶

15 years ago

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)
?>

down

Robin ¶

13 years ago

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
?>

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e dot sand at elisand dot com ¶

14 years ago

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).

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andre dot roesti at 7flex dot net ¶

13 years ago

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
?>

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Hector (hector-ordonez.com) ¶

7 years ago

Simon Neaves's answer is incomplete: negative integers will return false.

I recommend checking stackoverflow's answers:
http://stackoverflow.com/questions/6416763/checking-if-a-variable-is-an-integer-in-php

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davide dot renzi at gmail dot com ¶

7 years ago

I've found a faster way of determining an integer.
On my env, this method takes about half the time of using is_int(). 

Cast the value then check if it is identical to the original. 

<?php 
if ( (int) $n !== $n ) { 
    echo 'not is int'; 
} else { 
    echo 'is int'; 
} 
?>

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petepostma at gmail dot spam dot com ¶

11 years ago

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) );

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nicolas dot giraud at actiane dot com ¶

11 years ago

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 :)

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Vasiliy Makogon ¶

7 years ago

If you want detect integer of float values, which presents as pure int or float, and presents as string values, use this functions:

<?php 
function isInteger($val)
{
    if (!is_scalar($val) || is_bool($val)) {
        return false;
    }
    if (is_float($val + 0) && ($val + 0) > PHP_INT_MAX) {
        return false;
    }
    return is_float($val) ? false : preg_match('~^((:?+|-)?[0-9]+)$~', $val);
}

function isFloat($val)
{
    if (!is_scalar($val)) {
        return false;
    }
    return is_float($val + 0);
}

foreach ([
    '11111111111111111', 11111111111111111, // > PHP_INT_MAX - presents in PHP as float 
    1, '10', '+1', '1.1', 1.1, .2, 2., '.2', '2.', 
    '-2.', '-.2', null, [], true, false, 'string'
] as $value) {
    echo $value . ':' . gettype($value) . ' is Integer? - '  . (isInteger($value) ? 'yes' : 'no') . PHP_EOL;
    echo $value . ':' . gettype($value) . ' is Float? - '  . (isFloat($value) ? 'yes' : 'no') . PHP_EOL;
}
?>

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gabe at websaviour dot com ¶

20 years ago

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.

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me at rexxars dot com ¶

14 years ago

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+$.

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Julien Picalausa ¶

15 years ago

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

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-1

tudor at tudorholton dot com ¶

16 years ago

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)

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-1

ludvig dot ericson at gmail dot com ¶

17 years ago

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

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-1

lksunny at live dot hk ¶

6 years ago

<?
function check_num($num){
    if (preg_match("#^(-[0-9]{1,}|[0-9]{1,})$#", $num)){
        return true;
    }else{
        return false;
    }
}
var_dump(-1); //True
var_dump("-1"); //True
var_dump("1"); //True
var_dump("-999999999999999999"); //True
var_dump("999999999999999999"); //True
?>

negative number will be true :)

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-2

qlimmax at gmail dot com ¶

15 years ago

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",...)

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-2

Ender at soldat dot nl ¶

17 years ago

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.

down

-2

lclkk at urbanvagabond dot net ¶

20 years ago

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);
?>

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-3

Wryel Covo - ryryel[at]gmail[dot]com ¶

15 years ago

<?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";

}

?>

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-1

PHPDev esurf er s >dot ¶

8 years ago

This will check if something has an acceptable integer value, such as

a string with int value like "1" or "1.0"
a float with int value like 1.0
an int like 12e5

The same as is_numeric, but with integer values.

<?php

    function isIntValued($var) {
        if(is_numeric($var)) {
            $var=(float)$var;
            return ((float)(int)$var)===$var;
        }
        return FALSE;
    }

?>

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-2

mark at codedesigner dot nl ¶

15 years ago

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

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-3

ing dot alpi at gmail dot com ¶

10 years ago

Remember that some source of data always give a string data type.
That's the case with cookies and $_GET.
if you need to check against those values, try to convert them into numbers first.
The easiest way of doing so is adding a zero before your var, just like:

<?php
$var = '15'; // ...or $var = $_COOKIE['myvar'] or $var = 
$_GET['myvar']...

is_int($var);  // now returns FALSE

$var += 0;

is_int($var);  // now returns TRUE
?>

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-3

leonix at motd dot ru ¶

14 years ago

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);
}
?>

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-4

arturs at indigo dot lv ¶

11 years ago

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;
  }
}
?>

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-6

Roberto Rama ¶

14 years ago

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

?>

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-4

some at somewhere dot com ¶

10 years ago

<?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;
}
?>

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-8

paulo dot koch at g_mail dot com ¶

15 years ago

Don't over-engineer it.

<?php
function another_is_int($a){
    return ((string) $a) === ((string)(int) $a);
}
?>

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-7

thierryreeuwijk at hotmail dot com ¶

13 years ago

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

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-2

Anonymous ¶

8 years ago

Sometimes, we need to validate if a DECIMAL returned by a SQL database is an int or not. DECIMAL always return .000 at end of the string.

Then i use:
<?php
function isInteger($input){
{
    if(strpos($input,"."))
        $input=preg_replace("/\.$/","",rtrim(strval($input),"0"));
    return (ctype_digit($input));
}
?>

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-6

felix dot b at outlook dot com ¶

8 years ago

((int)$foo === $foo) does exactly the same as is_int($foo), but is faster performancewise, because PHP has quite an overhead on function calls.

As you can see the expression only returns true if the type (and value) of $foo is the same as int-casted $foo, which is only the case when foo is an int.

This applies to all the other is* functions aswell.

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