Constructors and its Types

A constructor is a member function with the same name as its class. Constructor does not have a return type and a return statement in the body of a constructor cannot have a return value. Constructor cannot be declared as virtual or static, nor can it be declared as const, volatile, or const volatile.
Example,

class ABC
{
public:
ABC ();       // Constructor of class ABC
}

Types of Constructors:

1.    Parameterized Constructors.
2.    Default Constructors.
3.    Copy Constructors.

The Constructors that can take arguments are called Parameterized Constructors, e.g.

class ABC {
int a, b;
public:
ABC(int i, int j) {
a=i;
b=j;
}

void show() {
cout << a << " " << b;
}
};
int main()
{
ABC ob(3, 5);
ob.show();
return 0;
}

A default constructor is a constructor that either has no parameters, or if it has parameters, all the parameters have default values.

A copy constructor is a special constructor which is used to create a new object as a copy of an existing object.

class ABC {
public:

ABC();            // default constructor, no arguments

X(int, int , int = 0);             // constructor

X(const X&);            // copy constructor
};

class Y {
public:

Y( int = 0);           // default constructor with one and default argument
Y(const Y&, int = 0);         // default argument and copy constructor
};