Gain insights into dynamic memory allocation, creating classes, and functions. Delve into inheritance, I/O, exception handling. Explore 90+ examples to master advanced C++ functionalities.

c.tar.gz

ConsoleInputJob

IOjob83

IOjob84

Lesson26and27

If you’re looking to sharpen up your C++ programming skills, then you’re in the right place. You will start with learning about dynamic memory allocation, how to create classes, and constructors. 

In the latter half of the course, inheritance, functions, I/O, exception handling, and more. Throughout the course, you will study over 90 carefully designed examples aimed to enhance your understanding of the C++ language.  

By the time you finish this course, you will be able to use more advanced functionality in your C++ programs.

C++ Programming for Experienced Engineers

# Problem
                        
How to define a **copy constructor**? 
                 
# Coding solution		                        

Here is a solution to the problem above.



// Program to demonstrate use of copy constructor

#include <iostream>


class Circle
{
	private :
		int radius ;
		float x, y ;

	public :
		Circle( )
		{
		}
		Circle ( int rr, float xx, float yy )
		{
			radius = rr ;
			x = xx ;
			y = yy ;
		}
		Circle ( Circle& c )
		{
			std::cout << "Copy constructor invoked" << std::endl ;
			radius = c.radius ;
			x = c.x ;
			y = c.y ;
		}
 		void showData( )
		{
			std::cout << "Radius = " << radius << std::endl ;
			std::cout << "X-Coordinate = " << x << std::endl  ;
			std::cout << "Y-Coordinate = " << y << std::endl ;
		}
} ;

int main( )
{
	Circle c1 ( 10, 2.5, 3.5 ) ;
	Circle c2 = c1 ;
	Circle c3 ( c1 ) ;
	
	c1.showData( ) ;
	c2.showData( ) ;
	c3.showData( ) ;
	
	return 0 ;
}


# Explanation	 	                        

Here object `c1` is constructed through the **three-argument** constructor. Objects `c2` and `c3` are constructed through the **copy constructor**. `c2` and `c3` cannot be constructed through the *normal three-argument constructor* since *they are also being initialized where they are defined*.
 
> Note the different ways of initialization of `c2` and `c3`. **Both** result in a **call to the copy constructor**. Also, note that during both the calls, `c1` is being passed to the copy constructor by **reference**. 

___

**Question:** Is it necessary for us to use a *reference in the argument* to the *copy constructor*? Can we *pass a value* instead?

**Answer:** *No*, because if we pass the *argument by value*, **its copy is constructed using the copy constructor**. *This means the copy constructor would call itself to make this copy*. 

>This process would go on and on until the compiler runs out of memory.

Hence, in the *copy constructor* the argument must always be passed by **reference**. Lastly, if we do not provide the *copy constructor* then the **compiler will provide it**.




Getting Off the Ground

Starters

Basic C++ Examples

Class Organization Examples

Class Constructor Examples

Classes and Objects Examples

More Classes and Objects Examples

Function Examples

Function Overloading Examples

Operator Overloading Examples

Free Store Examples

Inheritance Examples

Virtual Function Examples

Input Output Examples

Template Examples

Exception Handling Examples

STL Examples

Miscellaneous Examples

Conclusion

Copy Constructor

Problem