Basic Classes
To define a class, use the
class
keyword followed by the class name:
class Person { }
This code creates a Person
class. This is not a
very exciting class, because it lacks methods or properties.
Class names in PHP are case-insensitive,
so you cannot define both a Person
and a
PERSON
class.
Use this class name to instantiate a new instance of your object:
$rasmus = new Person;
Alternatively, to determine a class from
an object instance, use
get_class( )
:
$person = new Person;
print get_class($person)
Person
Even though class names are
case-insensitive, PHP 5 preserves their capitalization. This is
different from PHP 4, where PHP converts the name to lowercase. In
PHP 4, calling get_class( )
on an instance of the
Person
class produced person
.
PHP 5 returns the correct class name.
Properties
List class properties at the top of the class:
class Person { public $name; }
This creates a public
property named name
. When a property is public, it
can be read from and written to anywhere in the program:
$rasmus = new Person; $rasmus->name = 'Rasmus Lerdorf';
Properties in
PHP 4 are declared using a different syntax: var
.
This syntax is deprecated in favor of public
, but
for backward compatibility, var
is still legal.
The behavior of a property declared using public
and var
is identical.
Never use public
properties. Doing so makes it
easy to violate encapsulation. Always use accessor methods instead.
You don’t need to predeclare a property inside the class to use it. For instance: ...
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