Object Oriented Programming (OOP)

What is difference between “class” and “object”?

How to create new class inheriting all functions from a existing class?

• Create a child class

  [php]class Child extends Parent {
  <definition body>
  }[/php]

• A child class
  • has all the parent class’ member variables
  • has all the same parent class’ member functions
  • can modify (override) a function inherited from parent class

What is the difference between public, static, private and protected members?

• Public member
  • Can be accessed from outside the class
  • Can be accessed within the class
  • Can be accessed in different class which implements the class declaring that member
• Static member
  • Can be accessed like public member but no need to instantiate the class object
• Protected member
  • Can be accessed within the class
  • Can be accessed from inheriting class (extended class)
• Private member
  • Can be accessed within the class only
  • Can’t be accessed from inheriting class too (extended class)

What is the difference between interface and class?

• Interface is like a template that prepare all the function names in ahead
• Class can implement an interface and define the function content
• Different classes can define different contents for a same function name

What is difference between abstract class and normal class?

Javascript

How to create an object?

[js]
function labnoObj(ID, value) {
this._ID = ID;
this._value = value;
}
[/js]

How to add/remove an object to an array?

Add object to the end of an array

[js]
var arrObj = [];
var dataObj = new labnoObj(“1”, “value”);
arrObj.push(dataObj);
[/js]

Add object to the beginning of an array

[js]
//…
var dataObj2 = new labnoObj(“1”, “value”);
arrObj.unshift(dataObj2);
[/js]

How to check if an object exists in an array?

[js]
function containsObject(obj, list) {
var i;
for (i = 0; i < list.length; i++) { if (list[i]._ID == obj._ID) { return true; } } return false; } [/js]

How to use pointer in JS?

[js]
var x = 0;
function a(x)
{
x++;
}
a(x);
alert(x); //Here I want to have 1 instead of 0
[/js]
So, it should be
[js]
var x = {Value: 0};
function a(obj)
{
obj.Value++;
}
a(x);
document.write(x.Value); //Here i want to have 1 instead of 0
[/js]