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define

define

Defines a named constant

bool **define** string $constant_name mixed $value bool $case_insensitive

Defines a named constant at runtime.

constant_nameThe name of the constant.

Opmerking: > It is possible to constants with reserved or even invalid names, whose value can (only) be retrieved with . However, doing so is not recommended. define``constant

valueThe value of the constant.

Waarschuwing: > While it is possible to define constants, it is not recommended and may cause unpredictable behavior. resource

case_insensitive If set to true, the constant will be defined case-insensitive. The default behavior is case-sensitive; i.e. and represent different values. CONSTANT``Constant

Waarschuwing: > Defining case-insensitive constants is deprecated as of PHP 7.3.0. As of PHP 8.0.0, only false is an acceptable value, passing true will produce a warning.

Opmerking: > Case-insensitive constants are stored as lower-case.

return.success

Voorbeeld: Defining Constants

<?php
define("CONSTANT", "Hello world.");
echo CONSTANT; // outputs "Hello world."
echo Constant; // outputs "Constant" and issues a notice.

define("GREETING", "Hello you.", true);
echo GREETING; // outputs "Hello you."
echo Greeting; // outputs "Hello you."

// Works as of PHP 7
define('ANIMALS', array(
    'dog',
    'cat',
    'bird'
));
echo ANIMALS[1]; // outputs "cat"

?>

Voorbeeld: Constants with Reserved Names

 This example illustrates the  to define a
 constant with the same name as a
 .
 Since the resulting behavior is obviously confusing, it is not recommended
 to do this in practise, though.
*possibility*magic constant

<?php
var_dump(defined('__LINE__'));
var_dump(define('__LINE__', 'test'));
var_dump(constant('__LINE__'));
var_dump(__LINE__);
?>

bool(false)
bool(true)
string(4) "test"
int(5)

defined``constantConstants

Vorige ← constant Volgende defined →

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