What is an Object?

An object is a real instance of a class.

If a class is a blueprint, an object is the actual thing created from that blueprint.

Student mina;
Student riaz;

Here, mina and riaz are two different objects of the Student class.

Object Has Three Ideas

1. State

State means the data stored in the object.

Example:

name = "Mina"
marks = 85

2. Behavior

Behavior means what the object can do.

Example:

display details
update marks
check pass/fail

3. Identity

Identity means each object is distinct, even if two objects contain the same data.

Student a;
Student b;

a and b are separate objects.

Important Point

Each object has its own copy of non-static data members.

If mina and riaz both have a marks data member, changing mina's marks does not automatically change riaz's marks.

Example

#include <iostream>
#include <string>

class Student {
private:
    std::string name;

public:
    void setName(const std::string& studentName) {
        name = studentName;
    }

    void display() const {
        std::cout << name << '\n';
    }
};

int main() {
    Student first;
    Student second;

    first.setName("Mina");
    second.setName("Riaz");

    first.display();
    second.display();
}

Viva Answer

An object is an instance of a class. It has state, behavior, and identity. Each object has its own copy of non-static data members.

Quick Check

• What is an object?
• What is object state?
• What is object behavior?
• If two objects have the same data, are they the same object?