Learn PHP(5) classes and objects step by step_PHP tutorial

In this section, we will take a look at how to create a class and object in PHP.

1. Create a class

In PHP, creating a class is basically similar to that in C#/Java. Without further ado, let me show you the simplest example. :

Copy code The code is as follows:

class People
{
var $name;
public function GetName()
{
return $this->name;
}
public function SetName($name)
{
$this- >name=$name;
}
}

$p=new People();
$p->SetName("kym");
echo($ p->GetName());
?>

Here, we create a People class. Here are four key points to explain:

Chapter One is that in PHP, accessing properties (or methods) does not use our commonly used dot operator (.), but ->.

The second one is that in PHP, methods need to be marked with function, which is very similar to Javascript.

The third point is that when we declare a variable, we need to use var, which is very similar to Javascript.

The fourth point is that in PHP, there are also three access modifiers, public, protected, and private, which are the same as C#, so I won’t go into details.

Here, we find that we can use $p to directly access the $name attribute, then we need to control it as follows:

Copy code The code is as follows:

class People
{
private $name;
public function GetName()
{
return $this-> name;
}
public function SetName($name)
{
$this->name=$name;
}
}

At this time, we cannot access the $name attribute from the outside world.

Remember we mentioned variable functions above? Here we can also use variable functions to access object methods:

Copy code The code is as follows:

php
class People
{
private $name;
public function GetName()
{
return $this->name;
}
public function SetName ($name)
{
$this->name=$name;
}
}

$p=new People();
$get=" GetName";
$set="SetName";
$p->$set("kym");
echo($p->$get());
?> ;

2. Static methods (properties)

Declaring static methods (also called class methods) in PHP is very similar to that in C# of.

Copy code The code is as follows:

class DataBase
{
public static function CreateConnection()
{
echo("Success");
}
}
DataBase::CreateConnection();
?>

Similarly, the same goes for declaring static properties.

Copy code The code is as follows:

class DataBase
{
static $ connectionString="http://127.0.0.1";
public static function CreateConnection()
{
echo("Success");
}
}
echo(DataBase: :$connectionString);
DataBase::CreateConnection();
?>

3. Class constants

In C#, We use const to identify constants, the same in PHP.

Copy code The code is as follows:

class DataBase
{
const AUTHOR ="kym";
static $connectionString="http://127.0.0.1";
public static function CreateConnection()
{
echo("Success");
}
}
echo(DataBase::AUTHOR);
echo(DataBase::$connectionString);
DataBase::CreateConnection();
?>

4. Access static variables

We know that static properties (methods) belong to the class itself, and variables (methods) belong to the object itself, and the class itself exists before the object, then we How to access static variables (methods) in dynamic methods? In PHP, we are provided with the self keyword.

Copy code The code is as follows:

class DataBase
{
const AUTHOR ="kym";
static $connectionString="http://127.0.0.1";
public static function CreateConnection()
{
echo(self::$connectionString." Success") ;
}
}
echo(DataBase::AUTHOR);
echo(DataBase::$connectionString);
DataBase::CreateConnection();
?>

http://www.bkjia.com/PHPjc/321289.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/321289.htmlTechArticleIn this section, we will take a look at how to create a class and object in PHP. 1. Create a class In PHP, creating a class is basically similar to that in C#/Java. Without further ado, let me show you the most...