In object-oriented programming, a constructor is a special member method of a class that is executed when an object of that class is created. Constructors are responsible for initializing the data members of the class.

C++ allows the creation of parameterized constructors, which are constructors that can accept arguments. These arguments can be used to initialize the data members of the class with specified values.

To define a parameterized constructor in C++, follow these steps:

1. Declare the constructor in the class definition, inside the public section, specifying the desired parameters.

class MyClass {
public:
  MyClass(int value1, float value2);
};

1. Define the constructor outside the class definition, using the Class::Constructor syntax.

MyClass::MyClass(int value1, float value2) {
  // Initialize data members with the given values
}

1. Inside the constructor, assign the given values to the appropriate data members of the class.

MyClass::MyClass(int value1, float value2) {
  data_member1 = value1;
  data_member2 = value2;
}

Here’s an example that demonstrates the usage of a parameterized constructor:

#include <iostream>

class Rectangle {
private:
  int width;
  int height;

public:
  Rectangle(int w, int h) {
    width = w;
    height = h;
  }

  int calculateArea() {
    return width * height;
  }
};

int main() {
  Rectangle rectangle(5, 10);
  std::cout << "Area: " << rectangle.calculateArea() << std::endl;
  return 0;
}

In the example above, the Rectangle class has a parameterized constructor that takes two arguments: width and height. The constructor initializes the width and height data members with the given values. The calculateArea() member function calculates and returns the area of the rectangle.

Using parameterized constructors allows for more flexibility when creating objects of a class, as the objects can be initialized with specific values right at the time of creation.

#C++ #Constructors