Integers

Integers

An is a number of the set ℤ = {..., -2, -1, 0, 1, 2, ...}. int

Floating point numbersArbitrary precision / BCMathArbitrary length integer / GMP

Syntax

s can be specified in decimal (base 10), hexadecimal (base 16), octal (base 8) or binary (base 2) notation. The can be used to denote a negative . Intnegation operatorint

To use octal notation, precede the number with a (zero). As of PHP 8.1.0, octal notation can also be preceded with or . To use hexadecimal notation precede the number with . To use binary notation precede the number with . 0``0o``0O``0x``0b

As of PHP 7.4.0, integer literals may contain underscores () between digits, for better readability of literals. These underscores are removed by PHP's scanner. _

Voorbeeld: Integer literals

<?php
$a = 1234; // decimal number
$a = 0123; // octal number (equivalent to 83 decimal)
$a = 0o123; // octal number (as of PHP 8.1.0)
$a = 0x1A; // hexadecimal number (equivalent to 26 decimal)
$a = 0b11111111; // binary number (equivalent to 255 decimal)
$a = 1_234_567; // decimal number (as of PHP 7.4.0)
?>

Formally, the structure for literals is as of PHP 8.1.0 (previously, the or octal prefixes were not allowed, and prior to PHP 7.4.0 the underscores were not allowed): int``0o``0O

decimal     : [1-9][0-9]*(_[0-9]+)*
            | 0

hexadecimal : 0[xX][0-9a-fA-F]+(_[0-9a-fA-F]+)*

octal       : 0[oO]?[0-7]+(_[0-7]+)*

binary      : 0[bB][01]+(_[01]+)*

integer     : decimal
            | hexadecimal
            | octal
            | binary

The size of an is platform-dependent, although a maximum value of about two billion is the usual value (that's 32 bits signed). 64-bit platforms usually have a maximum value of about 9E18. PHP does not support unsigned s. size can be determined using the constant , maximum value using the constant , and minimum value using the constant . int``int``int``PHP_INT_SIZE``PHP_INT_MAX``PHP_INT_MIN

Integer overflow

If PHP encounters a number beyond the bounds of the type, it will be interpreted as a instead. Also, an operation which results in a number beyond the bounds of the type will return a instead. int``float``int``float

Voorbeeld: Integer overflow

<?php
$large_number = 50000000000000000000;
var_dump($large_number);         // float(5.0E+19)

var_dump(PHP_INT_MAX + 1);       // 32-bit system: float(2147483648)
                                 // 64-bit system: float(9.2233720368548E+18)
?>

Integer division

There is no division operator in PHP, to achieve this use the function. yields the . The value can be cast to an to round it towards zero, or the function provides finer control over rounding. int``intdiv``1/2``float``0.5``int``round

Voorbeeld: Divisions

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

Converting to integer

To explicitly convert a value to , use the cast. However, in most cases the cast is not needed, since a value will be automatically converted if an operator, function or control structure requires an argument. A value can also be converted to with the function. int``(int)``int``int``intval

If a is converted to an , then the result will be the unique resource number assigned to the by PHP at runtime. resource``int``resource

See also . Type Juggling

From booleans

false will yield  (zero), and true will yield
 (one).

0``1

From floating point numbers

When converting from  to , the number
will be rounded .
As of PHP 8.1.0, a deprecation notice is emitted when implicitly converting a non-integral float to integer which loses precision.

float``inttowards zero

Voorbeeld: Casting from Float

<?php

function foo($value): int {
  return $value;
}

var_dump(foo(8.1)); // "Deprecated: Implicit conversion from float 8.1 to int loses precision" as of PHP 8.1.0
var_dump(foo(8.1)); // 8 prior to PHP 8.1.0
var_dump(foo(8.0)); // 8 in both cases

var_dump((int) 8.1); // 8 in both cases
var_dump(intval(8.1)); // 8 in both cases
?>

If the float is beyond the boundaries of  (usually
 on 32-bit platforms and
 on 64-bit platforms),
the result is undefined, since the  doesn't
have enough precision to give an exact  result.
No warning, not even a notice will be issued when this happens!

int``+/- 2.15e+9 = 2^31``+/- 9.22e+18 = 2^63``float``int

Opmerking: > , and will always be zero when cast to . NaN``Inf``-Inf``int

Waarschuwing: > Never cast an unknown fraction to , as this can sometimes lead to unexpected results. int

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

 See also the .
warning about float
 precision

From strings

If the string is

or leading numeric then it will resolve to the
corresponding integer value, otherwise it is converted to zero
().

numeric0

From NULL

null is always converted to zero ().

0

From other types

Let op: > The behaviour of converting to is undefined for other types. Do rely on any observed behaviour, as it can change without notice. intnot