What is function Overloading and Overriding in PHP?

Overloading  :- 

Function overloading means you want more work or login from a function or 

you can use different login in a function.

You can not use same function in a class so for use this login you can use __call

magic function where you can pass method name and parameter and can add login

according to their parameter.

Take a look on code:-

class test
{
 public function __construct()
 {
 //Your logic for constructor
 }
 public function __call($method_name , $parameter)
 {
  if($method_name == "overlodedFunction") 

//Function overloading logic for function name overlodedFunction
  {
   $count = count($parameter);
   switch($count)
   {
    case "1":
    //Business log in case of overlodedFunction function has 1 argument
    echo "You are passing 1 argument";
    break;
    case "2": //Incase of 2 parameter
    echo "You are passing 2 parameter";
    break;
    case "3": //Incase of 2 parameter
    echo "You are passing 3 parameter";
    break;
    default:
    throw new exception("Bad argument");
   }
  }
  else
  {
   throw new exception("Function $method_name does not exists ");
  }
 }
}

$a = new test();
$a->overlodedFunction("sagar");
$a->overlodedFunction("techflirt" , "sagar","5454");

 Overriding  :- Function overridng means you can override a function 

which is mention in parent class by same name of function;

Example:

class Parent
{
 public function s1()
 {
  echo 1;
 }
 public function s2()
 {
  echo 2;
 }
}
class Child
 {
 function s2($a) //overriding function s2
 {
  echo "$a";
 }
}
$a = new Child();
$a->s2("sagar");//it will print sagar