Essential Methods for PHP Classes: A Comprehensive Guide

• The functions which are declared in a class are called methods.
• A class method is exactly similar to PHP functions.
• Declaring a method in a class is an easy task, use one of the keyword public, protected, or private followed by a method name.
  
  • public: The method can be accessed from outside the class.
  • private: No access is granted from outside the class.
  • protected: No access is granted from outside the class except a class that’s a child of the class with the protected property or method.
• A valid method name starts with a letter or underscores, followed by any number of letters, numbers, or underscores.
• The method body enclosed within a pair of braces that contain codes. The opening curly brace ( { ) indicates the beginning of the method code and the closing curly ( } ) brace indicates the termination of the method.
• If the method is not defined by the public, protected, or private then the default is public.
• Can access properties and methods of the current instance using $this (Format $this->property) for a non-static property.

Example:

After an object is instantiated, you can access the method of a class using the object and -> operator. In the following example customize_print() method will print a string with specific font size and color within an HTML paragraph element with the help of the PHP echo statement.

Syntax

<?php   
class Myclass
{
 public $font_size ="18px";
 public $font_color = "blue";
 public $string_name = "atnyla";
 public function customize_print()
 {
 echo "<p style=font-size:".$this->font_size.";color:".$this->font_color.";>".$this->string_name."</p>";
 }
}
$f = new MyClass;
echo $f->customize_print();
?>

Now change the value of font_size, font_color, and the string and check what the method custimize_print() returns.

Syntax

<?php   
class Myclass
{
 public $font_size ="18px";
 public $font_color = "blue";
 public $string_name = "w3resource";
 public function customize_print()
 {
 echo "<p style=font-size:".$this->font_size.";color:".$this->font_color.";>".$this->string_name."</p>";
 }
}
$f = new MyClass;
$f->font_size = "20px";
$f->font_color = "red";
$f->string_name = "Object Oriented Programming";
echo $f->customize_print();
?>

Another Example:

Example Code:

<?php
class Dress{  
	public $color = "red";  // The color of the dress 
	Public $fabric = "linen"; // The fabric of the dress 
	Public $design = "Slim Fit Blazer";//The design of the dress   

	Public function displayInfo(){ 
		echo "The info about the dress.</br>"; 
		echo $this->color."</br>"; 
		echo $this->fabric."</br>" ; 
		echo $this->design."</br>"; 
	} 

}
$dressObj = new Dress();
$dressObj->displayInfo();
?>

Example of this keyword

Example Code:

<?php
class Dress{  
	public $color = "red";  // The color of the dress 
	Public $fabric = "linen"; // The fabric of the dress 
	Public $design = "Slim Fit Blazer";//The design of the dress   
	
	Public function displayInfo(){ 
		echo "The info about the dress.</br>"; 
		echo $this->color."</br>"; 
		echo $this->fabric."</br>" ; 
		echo $this->design."</br>"; 
	} 
	Public function helloWorld(){ 
		echo $this->displayInfo(); 
	}
}
$dressObj = new Dress();
$dressObj->helloWorld();
?>

Example of parameterized function

Example Code:

<?php
class Dress{  
	public $color = "red";  // The color of the dress 
	Public $fabric = "linen"; // The fabric of the dress 
	Public $design = "Slim Fit Blazer";//The design of the dress   

	Public function displayInfo(){ 
		echo "The info about the dress."; 
		echo $this->color; 
		echo $this->fabric ; 
		echo $this->design; 
	} 
	
	Public function helloWorld($number1, $number2){ 
		return $number1 + $number2; 
	} 
}
$dressObj = new Dress();
echo $dressObj->helloWorld(20,30);
?>