Declaration of objects to class

🔷 What is an Object?

An object is an instance of a class. When you declare an object, you’re creating a real-world entity based on the structure defined in the class.

• A class is like a blueprint.
• An object is like the house built from that blueprint.

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🔷 Syntax for Declaring Objects

ClassName objectName;

You can also declare multiple objects of the same class:

ClassName obj1, obj2, obj3;

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🔷 Example: Declaring and Using an Object

#include <iostream>
using namespace std;

class Student {
  public:
    int rollNo;
    string name;

    void display() {
        cout << "Roll No: " << rollNo << ", Name: " << name << endl;
    }
};

int main() {
    Student s1; // Declaration of object 's1' of class Student

    // Assigning values
    s1.rollNo = 101;
    s1.name = "Alice";

    s1.display(); // Calling member function using object
    return 0;
}

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🔷 Explanation

• Student is a class.
• s1 is an object of the Student class.
• The object s1 is used to access data members and member functions using the dot operator (.): cppCopyEdits1.rollNo = 101; s1.display();

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🔷 Types of Object Declaration

1. Static Declaration

Declared in a normal way (as in the example above). Memory is allocated automatically when the function is called and deallocated when the function ends.

Student s1;  // Static object

2. Dynamic Declaration (Using Pointers)

Useful when you need objects at runtime.

Student *s1 = new Student;
s1->rollNo = 102;
s1->name = "Bob";
s1->display();

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🔷 Real-Life Analogy

Class	Object Example
Blueprint	Actual house
Car class	Honda, Toyota
Student class	Ram, Sita

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🔷 Diagram (Text-Based)

Class: Student
------------------------
| rollNo : int         |
| name : string        |
| display()            |
------------------------

Object: s1
------------------------
| rollNo = 101         |
| name = "Alice"       |
------------------------

s1.display() --> calls the display() method

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🔷 Summary

• Objects are instances of a class.
• You use objects to access class members (variables/functions).
• Use the dot operator (.) to access members: objectName.memberName
• You can declare objects statically or dynamically.