{"id":671,"date":"2021-03-25T02:55:28","date_gmt":"2021-03-25T02:55:28","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=671"},"modified":"2025-04-07T11:26:19","modified_gmt":"2025-04-07T11:26:19","slug":"php-protected","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-oop\/php-protected\/","title":{"rendered":"PHP protected"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn how to use the PHP protected<\/code> access modifier to allow child classes to access properties and methods of the parent class.<\/p>\n\n\n\n

Introduction to the PHP protected access modifier #<\/a><\/h2>\n\n\n\n

In the access modifier tutorial<\/a>, you learned about the public<\/code> and private<\/code> access modifiers. The public<\/code> properties and methods can be accessed from both inside and outside of the class while the private<\/code> properties and methods can be accessed only within the class.<\/p>\n\n\n\n

The protected<\/code> properties and methods can be accessed from the inside of the class and any class that extends the class.<\/p>\n\n\n\n

Like the private<\/code> and public<\/code> access modifier, you prefix the property name with the protected keyword to define a protected property:<\/p>\n\n\n

protected<\/span> $propertyName;<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
As well as a method:<\/p>\n\n\n
protected<\/span> function<\/span> methodName<\/span>()<\/span> \n<\/span>{\n\n   \/\/...<\/span>\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
PHP protected property example #<\/a><\/h2>\n\n\n\n
First, define the Customer<\/code> class that has a private property $name<\/code>:<\/p>\n\n\n
<?php<\/span>\n\nclass<\/span> Customer<\/span>\n<\/span>{\n\tprivate<\/span> $name;\n\n\tpublic<\/span> function<\/span> __construct<\/span>($name)<\/span>\n\t<\/span>{\n\t\t$this<\/span>->name = $name;\n\t}\n}<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
Second, define the VIP<\/code> class that extends the Customer<\/code> class. The VIP<\/code> class has a method getFormattedName()<\/code> that accesses the $name<\/code> property:<\/p>\n\n\n
<?php<\/span>\n\nclass<\/span> VIP<\/span> extends<\/span> Customer<\/span>\n<\/span>{\n\tpublic<\/span> function<\/span> getFormattedName<\/span>()<\/span>\n\t<\/span>{\n\t\treturn<\/span> ucwords($this<\/span>->name);\n\t}\n}<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
Third, create an instance of the VIP<\/code> class and call the getFormattedName()<\/code> method:<\/p>\n\n\n
<?php<\/span>\n\n$alex = new<\/span> VIP('alex ferguson'<\/span>);\necho<\/span> $alex->getFormattedName();<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
PHP issued the following error:<\/p>\n\n\n
PHP Notice:  Undefined property: VIP::$name in ...<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Since $name<\/code> property is private, you can only access it within the Customer<\/code> class. To allow the child class to access the $name<\/code> property, you can change it to a protected property like this:<\/p>\n\n\n
<?php<\/span>\n\nclass<\/span> Customer<\/span>\n<\/span>{\n\tprotected<\/span> $name;\n\n\tpublic<\/span> function<\/span> __construct<\/span>($name)<\/span>\n\t<\/span>{\n\t\t$this<\/span>->name = $name;\n\t}\n}<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
If you execute the script again, you’ll see the following in the output:<\/p>\n\n\n
Alex Ferguson<\/code><\/span><\/pre>\n\n\n
PHP protected method example #<\/a><\/h2>\n\n\n\n
Let’s take an example of using the protected methods.<\/p>\n\n\n\n
First, define the Customer<\/code> class:<\/p>\n\n\n
<?php<\/span>\n\nclass<\/span> Customer<\/span>\n<\/span>{\n\tprotected<\/span> $name;\n\n\tpublic<\/span> function<\/span> __construct<\/span>($name)<\/span>\n\t<\/span>{\n\t\t$this<\/span>->name = $name;\n\t}\n\n\tprotected<\/span> function<\/span> format<\/span>()<\/span>\n\t<\/span>{\n\t\treturn<\/span> ucwords($this<\/span>->name);\n\t}\n\n\tpublic<\/span> function<\/span> getName<\/span>()<\/span>\n\t<\/span>{\n\t\treturn<\/span> $this<\/span>->format($this<\/span>->name);\n\t}\n}<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
The Customer<\/code> class has the protected property $name<\/code> and protected method format()<\/code>. The format()<\/code> method returns the $name<\/code> with the first character of each word converted to uppercase. <\/p>\n\n\n\n
The Customer<\/code> class also has the public method getName()<\/code> that calls the format()<\/code> method to return the formatted name.<\/p>\n\n\n\n
Second, define the VIP<\/code> class that extends the Customer<\/code> class:<\/p>\n\n\n
\n<?php<\/span>\n\nclass<\/span> VIP<\/span> extends<\/span> Customer<\/span>\n<\/span>{\n\tprotected<\/span> function<\/span> format<\/span>()<\/span>\n\t<\/span>{\n\t\treturn<\/span> strtoupper($this<\/span>->name);\n\t}\n}<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
Third, create a new instance of the Customer<\/code> class and display the name:<\/p>\n\n\n
$bob = new<\/span> Customer('bob allen'<\/span>);\necho<\/span> $bob->getName(); \/\/ Bob Allen<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
 Bob Allen<\/code><\/span><\/pre>\n\n\n
In this example, the getName()<\/code> method invokes the format()<\/code> method of the Customer<\/code> class and returns the name with the first character of each word converted to uppercase.<\/p>\n\n\n\n
Finally, create a new instance of the VIP class and show the name:<\/p>\n\n\n
$alex = new<\/span> VIP('alex ferguson'<\/span>);\necho<\/span> $alex->getName(); \/\/ ALEX FERGUSON<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
ALEX FERGUSON<\/code><\/span><\/pre>\n\n\n
This time,  the getName()<\/code> method calls the format()<\/code> of the VIP<\/code> class instead of the Customer<\/code> class. Therefore, you see the name is converted uppercase.<\/p>\n\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
  • Use protected<\/code> properties and methods can only be accessed within the class and in any child classes of the class.<\/li><\/ul>\n
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The VIP class has the overriding<\/a> format()<\/code> method that returns the $name<\/code> with all characters converted to uppercase. The format()<\/code> method is also protected.<\/p>\n\n\n\n