Copy Constructor in C++ with example - Cyborg Coding

A copy constructor in C++ is a special constructor that is used to create a new object as a copy of an existing object. The copy constructor typically performs a deep copy of the object's properties, meaning that it creates a new object with separate memory for each property, rather than just copying references to the original object's properties.

A copy constructor is defined with a single parameter, which is a constant reference to an object of the same class. For example:

class MyClass {

private:

    int x;

    int y;

public:

    MyClass(int xVal, int yVal) : x(xVal), y(yVal) {}

    MyClass(const MyClass &other) : x(other.x), y(other.y) {}

    int getX() { return x; }

    int getY() { return y; }

};

In this example, "MyClass" has a parameterized constructor that takes two parameters, "xVal" and "yVal", and a copy constructor that takes a constant reference to an object of the same class as its parameter. The copy constructor initializes the properties "x" and "y" with the values of the properties of the other object.

MyClass myObject1(10, 20);

MyClass myObject2 = myObject1;

In this example, myObject1 is created with the parameterized constructor and initializes x and y to 10 and 20 respectively. myObject2 is created with the copy constructor and initializes x and y with the values of myObject1.

It is important to note that the copy constructor is called when an object is passed by value, returned by value, or when an object is constructed from another object of the same class. The copy constructor is also called when an object is initialized with the assignment operator.

It's also worth mentioning that C++11 and later versions provide a feature called "Copy elision" which allows the compiler to avoid calling copy constructors in certain cases, such as when an object is returned by value from a function, in order to improve performance.

In summary, a copy constructor in C++ is a special constructor that is used to create a new object as a copy of an existing object. The copy constructor typically performs a deep copy of the object's properties, meaning that it creates a new object with separate memory for each property, rather than just copying references to the original.