Static variables and methods

A static variable is accessed through class name followed by the scope resolution operator(::).

for Example:

( If class Name : A and Variable name is : x)

Then you can accessed it like this : A::x.

self keyword with scope resolution operator(::) is used to access “static variables” within class.

A Member function which is declared as “static” is accessed through class name with “scope resolution operator”.

Example 1:

<?php
 
    //definition of class.
	class User
	{
		public static $i=1;
		public  $j=1;
		
		public function getValue()
		{
			return $this->j." value :  " . self::$i;
		}
		
		public  function setValue($a)
		{
			self::$i = $a;
			$this->j = $a;
		}
     }

	 $User = new User();
	 $User->setValue(10);
	 echo $User->getValue();
	 
	 echo"<br>";
	 $User1 = new User();
	 echo $User1->getValue();
	 
	 echo"<br>";
	 $User2 = new User();
	 echo $User2->getValue();


?>

Example 2:

<?php

	  // definition of class.
	  class User
	  {
			public $name;
			public $age;
			public static $minimumPasswordLength = 6;
			
			public function Describe()
			{
				return $this->name . " is " . $this->age . " years old";
			}
			
			public static function ValidatePassword($password)
			{
				//if(strlen($password) >= self::$minimumPasswordLength)
				//	return true;
				//else
				//	return false;
			}
		
			public function set_name()
			{
				$this->name="Prakash";
				
			}
			public function get_name()
			{
				return $this->name;
				echo"<br>";
				
			}
			 public function set_age()
			{
				$this->age=45;
				
			}
			public function get_age()
			{
				return $this->age;
				echo"<br>";
				
			}
	 }
			
	$password = "test";
	
	if(User::ValidatePassword($password))
		echo "Password is valid!";
	else
		echo "Password is NOT valid!";
	
	 $User = new User();
	 echo $User->set_name();
	 
	 echo"<br>";
	 echo $User->get_name();
	 
	 echo $User->set_age();
	 
	 echo"<br>";
	 echo $User->get_age();
	 
?>