PHP Access Modifiers

Access modifiers are used to control where properties and methods can be accessed.

There are three access modifiers :

• public - From anywhere, a property or method can be accessed. As a result, this setting is the default.
• protected - Within the class and by classes descended from it, the property or method can be accessed.
• private - Only members of the class have access to the property or method.

Example 1 :- A simple program for different access modifier.

<?php
class Person {
  public $name;
  protected $gender;
  private $age;
}
$p1 = new Person();
$p1->name = 'Billgates'; // OK
$p1->gender = 'Male'; // ERROR
$p1->age = 55; // ERROR
?>

Try setting the name property and it will work (because the name property is public). But if you try to set the "gender" or "age" property, a fatal error will appear (because the gender and age property are protected and private) :

Example 2 :- Adding two public methods to access the private and protected properties.

<?php
class Person {
  public $name;
  protected $gender;
  private $age;
  public setGender($gender)
  {
    $this->gender = $gender;
  }
  public setAge($age)
  {
    $this->age = $age;
  }
}
$p1 = new Person();
$p1->name = 'Billgates';
$p1->setGender("Male");
$p1->setAge(55);
?>

Now, There will be a question on your mind? Why we have create public methods to access private members?

The answer is "To collect proper input data".

Example 3 :- Adding two public methods to access the private and protected properties.

<?php
class Person {
  public $age1;
  private $age2;
  function setAge2($age2)
  {
    if($age2 >= 18 && $age2 <= 60)
    {
        $this->age2 = $age2;
    }
  }
  function getAge2()
  {
    return $this->age2;
  }
}
$p1 = new Person();
$p1->age1=10000;
echo "Age 1 = " . $p1->age1 . "<br />";
$p1->setAge2(130);	//	It will not set
echo "Age 2 = " . $p1->getAge2() . "<br />";
$p1->setAge2(30);
echo "Age 2 = " . $p1->getAge2() . "<br />";
?>

The age1 property has invalid data because of direct access. But you cannot provide any invalid data on age2 property.

Note: You have a option to control your input data by using private modifier.