PHP 7.1.0 Released

Inteiros

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

Veja também:

Sintaxe

Inteiros podem ser especificados em notação decimal (base 10), hexadecimal (base 16), octal (base 8) ou binária (base 2), opcionalmente precedido de sinal (- ou +).

Inteiros binários literais estão disponíveis desde o PHP 5.4.0.

Para usar a notação octal, preceda o número com um 0 (zero). Para utilizar a notação hexadecimal, preceda o número com 0x. Para utilizar a notação binária, preceda o número com 0b.

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)
$a 0b11111111// número binário (equivalente ao 255 decimal)
?>

Formalmente, as estruturas para inteiros literais são:

decimal     : [1-9][0-9]*
            | 0

hexadecimal : 0[xX][0-9a-fA-F]+

octal       : 0[0-7]+

binary      : 0b[01]+

integer     : [+-]?decimal
            | [+-]?hexadecimal
            | [+-]?octal
            | [+-]?binary

O tamanho de um inteiro depende da plataforma, sendo um número aproximado a 2 bilhões o valor mais comum (número de 32 bits com sinal). Plataformas 64-bit possuem comumente o valor máximo de aproximadamente 9E18, exceto no Windows em versões anteriores ao PHP 7, onde são sempre 32-bit. 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, e o valor mínimo utilizando a constante PHP_INT_MIN desde o PHP 7.0.0.

Aviso

Em versões anteriores ao PHP 7, se um dígito inválido é passado para inteiro octal (por exemplo, 8 ou 9), o resto do número será ignorado. Desde o PHP 7, um erro de interpretação é emitido.

Overflow de inteiros

Se o PHP encontrar 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, retornará um ponto flutuante.

Exemplo #2 Overflow de inteiros em sistemas 32-bit

<?php
$large_number 
2147483647;
var_dump($large_number);                     // int(2147483647)

$large_number 2147483648;
var_dump($large_number);                     // float(2147483648)

$million 1000000;
$large_number =  50000 $million;
var_dump($large_number);                     // float(50000000000)
?>

Exemplo #3 Overflow de inteiros em sistemas 64-bit

<?php
$large_number 
9223372036854775807;
var_dump($large_number);                     // int(9223372036854775807)

$large_number 9223372036854775808;
var_dump($large_number);                     // float(9.2233720368548E+18)

$million 1000000;
$large_number =  50000000000000 $million;
var_dump($large_number);                     // float(5.0E+19)
?>

Não há um operador de divisão que resulta em um integer no PHP. 1/2 retorna o ponto flutuante 0.5. O valor pode ser convertido para inteiro para sempre truncar o número, ou usar a função round() que provê um fino controle sobre o arredondamento.

<?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 um dos modificadores (int) ou (integer). Entretanto, na maioria dos casos, o modificador não é necessário, já que o valor será automaticamente convertido se um operador, função ou estrutura de controle requerer um inteiro como argumento. Um valor também pode ser convertido para inteiro utilizando a função intval().

Se um recurso for convertido para um inteiro, resultará no número único do recurso, atribuído ao recurso pelo PHP em tempo de execução.

Veja também Manipulação de tipos.

De booleanos

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

De números de ponto flutuante

Conversão de números de ponto flutuante para inteiros, fará o número ser truncado.

Se o número convertido estiver além dos limites de um integer (geralmente +/- 2.15e+9 = 2^31 em plataformas 32 bit e +/- 9.22e+18 = 2^63 em plataformas 64-bit que não sejam Windows), o resultado é indefinido, por que o ponto flutuante não possui precisão suficiente para fornecer um resultado inteiro exato. Não se preocupe, pois nenhum aviso será emitido se isso acontecer!

Nota:

A partir do PHP 7.0.0, em vez de ser um valor indefinido e que varia de acordo com a plataforma, NaN e Infinity sempre serão zero quando convertido para integer, a partir do PHP 7.0.0.

Aviso

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

<?php
 
echo (int) ( (0.1+0.7) * 10 ); // imprime 7!
 
?>

Veja também o alerta sobre a precisão de número flutuante.

De outros tipos

Cuidado

O comportamento da conversão de um inteiro é desconhecido para outros tipos. Não confie em nenhum comportamento observado, pois ele pode mudar sem aviso.

add a note add a note

User Contributed Notes 20 notes

up
38
d_n at NOSPAM dot Loryx dot com
9 years ago
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);
?>
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16
Anonymous
1 year ago
Converting to an integer works only if the input begins with a number
(int) "5txt" // will output the integer 5
(int) "before5txt" // will output the integer 0
(int) "53txt" // will output the integer 53
(int) "53txt534text" // will output the integer 53
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22
php at richardneill dot org
3 years ago
A leading zero in a numeric literal means "this is octal". But don't be confused: a leading zero in a string does not. Thus:
$x = 0123;          // 83
$y = "0123" + 0     // 123
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25
rustamabd@gmail-you-know-what
9 years ago
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
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2
litbai
9 months ago
<?php
$ipArr
= explode('.', $ipString);
$ipVal = ($ipArr[0] << 24)
       + (
$ipArr[1] << 16)
       + (
$ipArr[2] << 8)
       +
$ipArr[3]
        ;
?>
1. the priority of bit op is lower than '+',so there should be brackets.
2. there is no unsighed int in PHP, if you use 32 bit version,the code above will get negative result when the first position of IP string greater than 127.
3. what the code actually do is calculate the integer value of transformed 32 binary bit from IP string.
up
10
darkshire
9 years ago
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.
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2
Anonymous
9 years ago
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'
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0
dewi at dewimorgan dot com
1 year ago
Note that the soft-typing of numbers in PHP means that some things become very difficult. For example, efficiently emulating the more common linear congruential generators (LCGs) for fast, deterministic, pseudo-randomness. The naive code to create the next value in a sequence (for power-of-2 values of $m) is:

$seed = ($seed * $a + $c) % $m;

...where $m, $a, and $c are values and data types carefully chosen such that repeating this operation will eventually generate every value in the range $0 to $m, with no repetition.

I can find no good commonly used LCGs which use PHP-compatible values. The LCG values used in by rand() in systems like Borland Delphi, Virtual Pascal, MS Visual/Quick C/C++, VMS's MTH$RANDOM, old versions of glibc, Numerical Recipes, glibc, GCC, ANSI C, Watcom, Digital Mars, CodeWarrior, IBM VisualAge C/C++, java.util.Random, Newlib, MMX... *all* fail when ported, for one of two reasons, and sometimes both:

- In PHP on 32 bit machines and all Windows machines, $m = 2^32 or larger requires UInt or even UInt64, or the result becomes negative.

- Large $a multiplied by an integer seed gets converted to a float64, but the number can be too long for the 53-bit mantissa, and it drops the least significant digits... but the LCG code above requires that the most significant digits should be lost.

These are two classes of problem to beware of when porting integer math to PHP,  and I see no clean and efficient way to avoid either one.

So if designing a cross-platform system that must work in PHP, you must select LCG values that fit the following criteria:
$m = 2^31 or less (PHP limitation). Recommend: 2^31.
$a = Less than 2^22 (PHP limitation); $a-1 divisible by all prime factors of $m; $a-1 divisible by 4 if $m is. Recommend: 1+(4*(any prime <= 1048573)).
$c = smaller than (2^53-($m*$a)) (PHP limitation); relatively prime with $m. Recommend: any prime <= 23622320123.
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-1
Jacek
9 years ago
On 64 bits machines max integer value is 0x7fffffffffffffff (9 223 372 036 854 775 807).
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-4
pere dot cil at wanadoo dot fr
5 years ago
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
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-3
Anonymous
12 years ago
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;
    }
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-5
wbcarts at juno dot com
8 years ago
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!
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-5
popefelix at gmail dot com
9 years ago
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.
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-8
eric
8 years ago
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
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-8
rickard_cedergren at yahoo dot com
11 years ago
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('');
      }
   }
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-9
php at keith tyler dot com
5 years ago
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.
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-11
Hamza Burak Ylmaz
8 years ago
<?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
?>
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-16
jmw254 at cornell dot edu
10 years ago
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";
}
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-16
sean dot gilbertson at gmail dot com
7 years ago
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
?>
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-26
Richard
5 years ago
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).
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