Inteiros

Um inteiro é um número do conjunto Z = {..., -2, -1, 0, 1, 2, ...}.

Veja também: , e .

Sintaxe

Inteiros podem ser especificados em notação decimal (base 10), hexadecimal (base 16) ou octal (base 8), opcionalmente precedido de sinal (- ou +).

Para usar a notação octal, você precisa preceder o número com um 0 (zero). Para utilizar a notação hexadecimal, preceda número com 0x.

Exemplo #1 Literais inteiras

<?php
$a = 1234; // número decimal
$a = -123; // um número negativo
$a = 0123; // número octal (equivalente a 83 em decimal)
$a = 0x1A; // número hexadecimal (equivalente a 26 em decimal)
?>
Formalmente, as possíveis representação de inteiros são: 
decimal     : [1-9][0-9]*
            | 0
hexadecimal : 0[xX][0-9a-fA-F]+
octal       : 0[0-7]+
integer     : [+-]?decimal
            | [+-]?hexadecimal
            | [+-]?octal
O tamanho de um inteiro é dependente de plataforma, sendo um número aproximado a 2 bilhões o valor mais comum (número de 32 bits com sinal). O PHP não suporta inteiros sem sinal. O tamanho do inteiro pode ser determinado pela constante PHP_INT_SIZE, e seu o valor máximo com a constante PHP_INT_MAX desde o PHP 4.4.0 e PHP 5.0.5.
Aviso

Se um dígito inválido é passado para inteiro octal (i.e. 8 ou 9), o resto do número é ignorado.

Exemplo #2 Octal weirdness

<?php
var_dump(01090); // 010 octal = 8 decimal
?>

Overflow de inteiros

Se você especifica um número além dos limites do tipo inteiro, ele será interpretado como um ponto flutuante. Assim, uma operação que resulte em um número além dos limites do tipo inteiro, um ponto flutuante será retornado.

<?php
$ numero_grande =  2147483647;
var_dump($numero_grande);
// saida: int(2147483647)

$numero_grande =  2147483648;
var_dump($numero_grande);
// saida: float(2147483648)

// é válido também para inteiros hexadecimais entre 2^31 e 2^32-1:
var_dump( 0xffffffff );
// output: float(4294967295)

// porém não é válido para hexadecimais com valores acima de 2^32-1:
var_dump( 0x100000000 );
// output: int(2147483647)

$milhao = 1000000;
$numero_grande =  50000 * $milhao;
var_dump($numero_grande);
// saida: float(50000000000)
?>
Aviso

Infelizmente, há um bug no PHP que faz que ele nem sempre trabalhe corretamente quando há números negativos envolvidos. Por exemplo, quando você faz -50000 * $milhao, o resultado será -429496728. Entretanto, quando ambos os operadores são positivos, isso não ocorre.

Isto foi resolvido no PHP 4.1.0.

Não há operador de divisão inteira no PHP. 1/2 retorna o ponto flutuante 0.5. Você pode moldar (cast) o valor para inteiro para sempre truncar o número, ou você pode usar a função .

<?php
var_dump(25/7);         // float(3.5714285714286)
var_dump((int) (25/7)); // int(3)
var_dump(round(25/7));  // float(4) 
?>

Convertendo para inteiro

Para converter explicitamente um valor para inteiro, utilize-se dos modificadores (int) ou (integer). Entretanto, na maioria dos casos, você não precisa utilizar o modificador, desde que qualquer valor será automaticamente convertido se um operador, função ou estrutura de controle requerer um argumento inteiro. Você também pode converter o valor de um inteiro com a função .

Veja também .

de

FALSE será retornado como 0 (zero), e TRUE como 1 (um).

De

Quando convertendo de números de ponto flutuante para inteiros, o número será truncado.

Se o número convertido estiver além dos limites de um inteiro (usualmente +/- 2.15e+9 = 2^31), o resultado é indefinido, mesmo porque o ponto flutuante não tem a mesma precisão para fornecer um resultado inteiro exato. Não se preocupe, pois nenhum aviso será emitido neste caso!

Aviso

Nunca modifique uma fração desconhecida para inteiro, porque isto pode fornecer resultados inesperados as vezes.

<?php
echo (int) ( (0.1+0.7) * 10 ); // imprime 7!
?>
Para maiores informações, veja o .

De outros tipos

Cuidado

O comportamento da conversão de um inteiro é indefinido de outros tipos. Atualmente, o comportamento é o mesmo como se primeiro o valor fosse . Entretanto, não confie neste comportamento, pois ele pode mudar sem aviso.

User Contributed Notes

Richard
Integer arithmetic in PHP is more accurate than one might think. On a 32-bit system, the largest value that can be held in an INT is  2147483647.
However, a FLOAT can accurately hold integer values up to 10000000000000.
(this is because the significand precision of a double is 53-bits).
php at keith tyler dot com
If you need to convert a numeric string (or more to the point, an object that represents a numeric value) that is greater then PHP_INT_MAX, and you don't have GMP or BCMath installed, you can cast to float.

For example, when using SimpleXMLElement, you sometimes have to cast the extracted values, such as xml attributes, because they are returned as SimpleXMLElements and not their values' native types. While print() has no trouble with converting them, other functions, such as max(), might not.

But if you cast such a value with (int), and it is over PHP_INT_MAX, you will just get PHP_INT_MAX (and vice versa for negative numbers).

The Q&D no-muss solution is to cast to (float) instead.
pere dot cil at wanadoo dot fr
Please also note that the maximum stored in the integer depends on the platform / compilation; on windows xp 32 bits, the following value:

0x5468792130ABCDEF

echoes to:

6.0822444802213E+18 (cast to float)

On a fully 64 bits system, it echoes to:

6082244480221302255
iletras at yahoo dot com
//This is a (simpler ?) function to return number of digits of an integer.

//function declaration
function count_digit($number) {
  return  strlen((string) $number);
}

//function call
$num = 12312;
$number_of_digits = count_digit($num); //this is call :)
echo $number_of_digits;
//prints 5
sean dot gilbertson at gmail dot com
You can make a signed, negative integer an unsigned integer (in string form) by doing the following:

<?php
$unsigned = sprintf('%u', -5);

echo $unsigned; // prints 4294967291
?>
Giovanni
why not just using logarithms?

$num_of_digits = (int)(log($num,$base) +1);

I think this should be more performant (as it relies on the math coprocessor) and it could be extended to number of digits representing the number in any base, not just decimal
Hamza Burak Ylmaz
<?php
//This is a simple function to return number of digits of an integer.

//function declaration
function count_digit($number)
{
    $digit = 0;
    do
    {
        $number /= 10;      //$number = $number / 10;
        $number = intval($number);
        $digit++;   
    }while($number!=0);
    return $digit;
}

//function call
$num = 12312;
$number_of_digits = count_digit($num); //this is call :)
echo $number_of_digits;
//prints 5
?>
wbcarts at juno dot com
PHP offers a slew of built-in functions and automatic type-casting routines which can get pretty complicated. But most of the time, you still have to take matters into your own hands and allow PHP to do its thing. In that case, and something that has NOT been mentioned, is how to construct your code. To keep things simple, I divide all my scripts in half. The top half gives my scripts the "capability" they need, and the lower half is the actual code to be "run" or "executed".

<?php
/*
 * build the program's capability - define variables and functions...
 */
$item_label = '';        // type string
$item_price = 0.0;       // type float
$item_qty = 1;           // type integer
$item_total = 0.0;       // type float - to set use calculate()

function calculate(){
  global $item_price, $item_qty, $item_total;
  $item_price = number_format($item_price, 2);
  $item_total = number_format(($item_price * $item_qty), 2);
}

function itemToString() {
  global $item_label, $item_price, $item_qty, $item_total;
  return "$item_label [price=\$$item_price, qty=$item_qty, total=\$$item_total]";
}

/*
 * run the program - set data, call methods...
 */
$item_label = "Coffee";
$item_price = 3.89;
$item_qty = 2;
calculate();           // set $item_total
echo itemToString();   // -> Coffee [price=$3.89, qty=2, total=$7.78]

$item_label = "Chicken";
$item_price = .80;     // per lb.
$item_qty = 3.5;       // lbs.
calculate();           // set $item_total
echo itemToString();   // -> Chicken [price=$0.80, qty=3.5, total=$2.80]
?>
Note: All type-casting is done by PHP's built-in number_format() method. This allows our program to enter any number (float or int) on item price or quantity in the runtime part of our script. Also, if we explicitly cast values to integer in the capability part of our script, then we start getting results that may not be desirable for this program. For example, if in the calculate method we cast item_qty to integer, then we can no longer sell chicken by the pound!
dbmuller at gmail dot com
be careful relying on PHP's data type handling.  I have a class that handles database calls and in there a function to handle types and formatting them for insertion.

<?php
case constants::int:
  $returnString = ($valueString >= 0) ? $valueString : "null";
  break;
?>

Will evaluate to false if a user enters "0" since PHP thinks that the 0 is a Boolean.  The following code fixes it:

<?php
case constants::int:
  $returnString = ((int)$valueString >= 0) ? (int)$valueString : "null";
 break;

?>
rustamabd at gmail dot com
Be very careful with code that relies on integer overflow. Negative overflow is handled differently on different platforms. For example, this code:
<?php
  echo (int)-3000000000; // a 32bit negative overflow
?>
... outputs 1294967296 on Windows, and -2147483648 on FreeBSD.
(Tested with php 5.2.6, freebsd 7.0)
eric
In response to the comment by me at troyswanson dot net:

-2147483648 falls into the range of 32 bit signed integers yet php treats it as a float.  However, -2147483647-1 is treated as an integer.

The following code demonstrates:
<?php
    var_dump(-2147483648); //float(-2147483648)
    var_dump(-2147483647 - 1); //int(-2147483648)
?>

This is probably very similar to the MS C bug which also treats -2147483648 as an UNSIGNED because it thinks it's out of the range of a signed int.

The problem is that the parser does not view "-x" as a single token, but rather as two, "-" and "x".  Since "x" is out of the range of an INT, it is promoted to float, even though in this unique case, "-x" is in the range of an int.

The best cure is probably to replace "-2147483648" with "0x80000000", as that is the hexadecimal equivalent of the same number.

Hope that helps explain what's going on

Peace

 - Eric / fez
winterheat
PHP_INT_SIZE seems to be 8 when it is 64 bit integers... so 8 means the number of bytes, or number of 8-bits.
Elliott Brueggeman
Don't forget about the integer minimum value. From my experimentation, the lowest valid integer is (PHP_INT_MAX * -1)-1. All values smaller than this fail the is_int() test, even though the may appear to act normally during mathematic operations. More info on this:
bart at NOvankuikSPAM dot nl
When handling very large numbers in PHP, you'll notice they get cut off at hexadecimal 7FFFF FFFF. Sometimes, you don't need to use these numbers in an actual calculation in PHP (i.e. just editing and displaying), and just need to save them in a database.

In that case, you can let MySQL handle the conversion from and to hexadecimal notation. In the example below, engineers need to save hexadecimal addresses up to FFFF FFFF. To update such a value in MySQL, use the following query, where 'addr' is a column with type unsigned integer(10).

<?php

        $query = "
        UPDATE hardware_register
        SET    name = ?,
               type = ?,
               addr = conv(?, 16, 10)
        WHERE  id = ?
        ";

?>

And selecting:
<?php
    $query = "
    SELECT name, type, conv(addr, 10, 16)
    FROM   hardware_register
    WHERE  id = ?
    ";

?>

Note that you'll have to treat the resulting addr column as a string everywhere in PHP. You can't do conversions like:

<?php
    $addr_decimal = sprintf("%X", $addr_column);
?>

because that'll result in $addr_decimal having the cut-off, maximum int value.
autotelic at NOOOOSPAM dot hotmail dot com
A note about converting IP addresses for storage in database.  For MySQL, this is unnecessary as it has built in support via the INET functions.  Also, there is no need to use BIGINT.  UNSIGNED INT is, at 4 bytes, the perfect size for holding an IP (column must be defined as UNSIGNED).  This can basically halve the storage size, as BIGINT is an 8 byte data type.

INET_ATON() converts a dotted IP string to INT:
INSERT table(ip) VALUES(INET_ATON('127.0.0.1'));

INET_NTOA() converts an INT to dotted IP string:
SELECT INET_NTOA(ip) FROM table
returns '127.0.0.1'

Details:
darkshire
d_n at NOSPAM dot Loryx dot com
13-Aug-2007 05:33
Here are some tricks to convert from a "dotted" IP address to a LONG int, and backwards. This is very useful because accessing an IP addy in a database table is very much faster if it's stored as a BIGINT rather than in characters.

IP to BIGINT:
<?php
  $ipArr    = explode('.',$_SERVER['REMOTE_ADDR']);
  $ip       = $ipArr[0] * 0x1000000
            + $ipArr[1] * 0x10000
            + $ipArr[2] * 0x100
            + $ipArr[3]
            ;
?>

This can be written in a bit more efficient way:
<?php
  $ipArr    = explode('.',$_SERVER['REMOTE_ADDR']);
  $ip       = $ipArr[0]<<24
            + $ipArr[1]<<16
            + $ipArr[2] <<8
            + $ipArr[3]
            ;
?>

shift is more cheaper.
Paul
"always round it downwards"

It seems to truncate, or round toward zero, rather than downward. If the float is negative, it is rounded up.
d_n at NOSPAM dot Loryx dot com
Here are some tricks to convert from a "dotted" IP address to a LONG int, and backwards. This is very useful because accessing an IP addy in a database table is very much faster if it's stored as a BIGINT rather than in characters.

IP to BIGINT:
<?php
  $ipArr    = explode('.',$_SERVER['REMOTE_ADDR']);
  $ip       = $ipArr[0] * 0x1000000
            + $ipArr[1] * 0x10000
            + $ipArr[2] * 0x100
            + $ipArr[3]
            ;
?>

IP as BIGINT read from db back to dotted form:

Keep in mind, PHP integer operators are INTEGER -- not long. Also, since there is no integer divide in PHP, we save a couple of S-L-O-W floor (<division>)'s by doing bitshifts. We must use floor(/) for $ipArr[0] because though $ipVal is stored as a long value, $ipVal >> 24 will operate on a truncated, integer value of $ipVal! $ipVint is, however, a nice integer, so
we can enjoy the bitshifts.

<?php
        $ipVal = $row['client_IP'];
        $ipArr = array(0 =>
                    floor(  $ipVal               / 0x1000000) );
        $ipVint   = $ipVal-($ipArr[0]*0x1000000); // for clarity
        $ipArr[1] = ($ipVint & 0xFF0000)  >> 16;
        $ipArr[2] = ($ipVint & 0xFF00  )  >> 8;
        $ipArr[3] =  $ipVint & 0xFF;
        $ipDotted = implode('.', $ipArr);
?>
me at troyswanson dot net
This note applies to machines that are using a 32 bit integer size.  I imagine the same results occur in 64 bit machines as well (with the number 2^63-1).

-2147483648 falls into the range of 32 bit signed integers (0b10000000000000000000000000000000), yet php treats it as a float.  However, -2147483647-1 is treated as an integer.

The following code demonstrates:
<?php
    var_dump(-2147483648); //float(-2147483648)
    var_dump(-2147483647 - 1); //int(-2147483648)
?>

Regards
Jacek
On 64 bits machines max integer value is 0x7fffffffffffffff (9 223 372 036 854 775 807).
To force the correct usage of 32-bit unsigned integer in some functions, just add '+0'  just before processing them.

for example
echo(dechex("2724838310"));
will print '7FFFFFFF'
but it should print 'A269BBA6'

When adding '+0' php will handle the 32bit unsigned integer
correctly
echo(dechex("2724838310"+0));
will print 'A269BBA6'
popefelix at gmail dot com
Be careful when using integer conversion to test something to see if it evaluates to a positive integer or not.  You might get unexpected behaviour.

To wit:
<?php
error_reporting(E_ALL);
require_once 'Date.php';

$date = new Date();
print "\$date is an instance of " . get_class($date) . "\n";
$date += 0;
print "\$date is now $date\n";
var_dump($date);

$foo = new foo();
print "\$foo is an instance of " . get_class($foo) . "\n";
$foo += 0;
print "\$foo is now $foo\n";
var_dump($foo);

class foo {
    var $bar = 0;
    var $baz = "la lal la";
    var $bak;

    function foo() {
        $bak = 3.14159;
    }
}
?>

After the integer conversion, you might expect both $foo and $date to evaluate to 0.  However, this is not the case:

$date is an instance of Date

Notice: Object of class Date could not be converted to int in /home/kpeters/work/sketches/ObjectSketch.php on line 7
$date is now 1
int(1)
$foo is an instance of foo

Notice: Object of class foo could not be converted to int in /home/kpeters/work/sketches/ObjectSketch.php on line 13
$foo is now 1
int(1)

This is because the objects are first converted to boolean before being converted to int.
rustamabd@gmail-you-know-what
Be careful with using the modulo operation on big numbers, it will cast a float argument to an int and may return wrong results. For example:
<?php
    $i = 6887129852;
    echo "i=$i\n";
    echo "i%36=".($i%36)."\n";
    echo "alternative i%36=".($i-floor($i/36)*36)."\n";
?>
Will output:
i=6.88713E+009
i%36=-24
alternative i%36=20
jmw254 at cornell dot edu
Try this one instead:

function iplongtostring($ip)
{
    $ip=floatval($ip); // otherwise it is capped at 127.255.255.255

    $a=($ip>>24)&255;
    $b=($ip>>16)&255;
    $c=($ip>>8)&255;
    $d=$ip&255;

    return "$a.$b.$c.$d";
}
rickard_cedergren at yahoo dot com
When doing large subtractions on 32 bit unsigned integers the result sometimes end up negative. My example script converts a IPv4 address represented as a 32 bit unsigned integer to a dotted quad (similar to ip2long()), and adds a "fix" to the operation.

   /**************************
    * int_oct($ip)
    * Convert INTeger rep of IP to octal (dotted quad)
    */
   function int_oct($ip) {

      /* Set variable to float */
      settype($ip, float);

      /* FIX for silly PHP integer syndrome */
      $fix = 0;
      if($ip > 2147483647) $fix = 16777216;

      if(is_numeric($ip)) {
         return(sprintf("%u.%u.%u.%u",
                $ip / 16777216,
                (($ip % 16777216) + $fix) / 65536,
                (($ip % 65536) + $fix / 256) / 256,
                ($ip % 256) + $fix / 256 / 256
                )
     );
      }
      else {
         return('');
      }
   }
Sometimes you need to parse an unsigned
32 bit integer. Here's a function I 've used:
                                                                               
    function parse_unsigned_int($string) {
        $x = (float)$string;
        if ($x > (float)2147483647)
            $x -= (float)"4294967296";
        return (int)$x;
    }