how to use a constructor c++ code example

Example 1: cpp class constructor

class MyClass {     // The class
  public:           // Access specifier
    MyClass() {     // Constructor
      cout << "Hello World!";
    }
};

Example 2: formats of constructor in c++

Line::Line( double len): length(len) {
   cout << "Object is being created, length = " << len << endl;
}