Bhavya Chanan

Let us take a simple example of a student dealing with object and classes for now.

Think of a student. I want to know more about the student. So in order to know a student, I need to have the details of the student. So to have the above thing precise, I need to answer simple questions to get straight to the point.

What is the name of the student? Each student has a name (Ram, Raman, Raju and many more). Many students can have the same name. What is the unique identity number of a student? Every student enrolled somewhere would have some unique identity that makes him different from other students. For example, there could be more than one student with the name Shubham. You may say that the last name of the student could differ. For example -> Student A is - Shubham Singh.

Student B is- Shubham Agarwal and so on and on. 

But there could be many students with the same first name and last name. So this is also not uniquely identified. That is why each student is associated with a unique identification number which may be a rollno, uid or studentid, whatever you may call. This uid, for instance, is different for every student, and thus it identifies a student uniquely.

In which class our student is in?

The student is a school that belongs to a particular class which he attends daily as per his curriculum.

Ram is in class 6th.

Mohawk is in class 8th.

What is the performance rank of the student?

According to his performance in different subjects, we can calculate a performance rank of a student concerning other students performance. For example, in a class of 100 students, Rahul came 2nd -> performance rank = 2 and on the other hand, Rohit came 97th -> performance rank = 97.

Now let's pile up our details for a student. We understood that each student has a name, a unique identifier value, a class in which he studies and a performance ranks. If we categorise them, we can call the student to have four properties:

• Name
• Uid
• Class/Standard
• Rank

Thus we conclude that each student has these four properties.

Name Uid Standard Rank.

Examples:

Name is Bhavya Uid is 12 Standard is 5 Rank is 17

Name is Vishesh Uid is 67 Standard is 7 Rank is 22

Name is Rahul Uid is 39 Standard is 6 Rank is 11

Again, I must repeat myself and tell you that each of these three students has the same properties as Name, Uid, Standard and Rank. It would repeat for all the students. So can't we create a class - Student and categorise all of them under the class Student.

Yeah, you heard it right! The student is a class, and all the students would be the object under this class. 

An entity that has a state and behaviour is known as an object.

A class is a group of objects which have common properties. It is a template or blueprint from which objects are created and is a logical entity.

In other words, a class represents the set of properties or methods that are common to all objects of one type.

We will see this definition everywhere for an object and a class, but it wasn't easy to comprehend and understand.

We can understand that each student has some property and states that can be changed about the above example.

Student1 has the name Bhavya and uid 12, who is in 5th standard and achieved a performance rank of 17.

Now his performance rank can change and so his standard in next year. Maybe his uid also changes if new enrollments are there, and in any case, he can wish to change his name. So the properties of a student can change.

But all the properties are common to all the students. So we can categorise them under a class called - Student.

I hope now it is easier to comprehend that a student is a class or blueprint of familiar objects and a particular student is an object to this class.

Students named Bhavya, Vishesh and Rahul, are three different objects under the template Student because they have the same properties like Name, Uid, Standard and Rank.

Now, if we discuss a student's behaviours, we can say a student study, play, and there could be a lot of everyday activities that the student performs. These could be addressed as the standard functionalities which every student performs and could put inside a class. We can see a class like this :

class Student

{

property->name

property->uid

property->standard

property->rank

}

Similarly, we would have seen excel sheets with different columns in them. Each column would have separate entries at different levels called rows. We call each column name a field.

Let us again take an example, and then we will compare this to the class structure that we understood above.

Every company owns employees who work under that company.

So in our example, we will consider Employee as a Table.

This Employee table would have different columns as :

Name

Id

Age

Designation

Salary

So in excel, if we create an Employee sheet and call it an Employee table, it would have all these Five columns under this. Each Employee would have all these five properties or fields. Each Employee would be called a record.