IMPRESS dotted_line CONTACT dotted_line search dotted_line Kontakt dotted_line sitemap dotted_line print
69 PHP-Resource users online

Switch to another languags Deutsch aktuelle Sprache Englisch
php-resource

PHP Manual


Class Constants

It is possible to define constant values on a per-class basis remaining the same and unchangeable. Constants differ from normal variables in that you don't use the $ symbol to declare or use them.

The value must be a constant expression, not (for example) a variable, a property, a result of a mathematical operation, or a function call.

It's also possible for interfaces to have constants. Look at the interface documentation for examples.

As of PHP 5.3.0, it's possible to reference the class using a variable. The variable's value can not be a keyword (e.g. self, parent and static).

Example #1 Defining and using a constant

<?php
class MyClass
{
    const 
constant 'constant value';

    function 
showConstant() {
        echo  
self::constant "\n";
    }
}

echo 
MyClass::constant "\n";

$classname "MyClass";
echo 
$classname::constant "\n"// As of PHP 5.3.0

$class = new MyClass();
$class->showConstant();

echo 
$class::constant."\n"// As of PHP 5.3.0
?>

Example #2 Static data example

<?php
class foo {
    
// As of PHP 5.3.0
    
const bar = <<<'EOT'
bar
EOT;
}
?>

Unlike heredocs, nowdocs can be used in any static data context.

Note:

Nowdoc support was added in PHP 5.3.0.




Comments to the PHP manual
Write new comment
 



 

New Tutorial entries

Migration einer PHP 5 App auf PHP 7

Dieses PHP 7 Tutorial zeigt dir, wie du dein PHP5 Script auf PHP7 umstellst.

Berni | Category: PHP
PHP 7 Virtual Machine

Dieser Artikel zielt darauf ab, einen Überblick über die Zend Virtual Machine, wie es in PHP 7 gefunden wird.

Berni | Category: PHP
plotting masters - a professional guide - Teil II

Grafische Interpolation und Bestapproximation von numerischen Wertepaaren: Wir wollen Punkte auf einer Zeichenebene über verschiedene Verfahren miteinander verbinden.

EVAMasters | Category: PHP