Creating Objects

Creating an object from a class is called instantiation.

ClassName objectName;

Example:

Student student;

Object Creation Looks Like Variable Declaration

Built-in type:

int age;

User-defined class type:

Student student;

Both declare a variable. The second variable is an object.

Multiple Objects

#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();
}

first and second are separate objects.

Stack Objects

Most beginner objects are created like this:

Student student;

This object is destroyed automatically when its scope ends.

Dynamic Objects

You can create objects dynamically:

Student* student = new Student();
delete student;

This teaches the basic mechanism, but modern C++ usually prefers smart pointers:

#include <memory>

auto student = std::make_unique<Student>();

You will study ownership more deeply later.

Connection to Constructors

When an object is created, its constructor is called.

For now, remember:

Student student; // creates object and calls constructor

Constructors are covered in Chapter 4.

Viva Answer

Creating an object from a class is called instantiation. Objects can be created like normal variables, and each object gets its own non-static data. When an object is created, its constructor is called.

Quick Check

• What is instantiation?
• Are first and second the same object?
• When is a stack object destroyed?
• What happens when an object is created?