In the given C++ language program, a class "TestClass " is defined, which contains a parameterized constructor and default constructor.
In the parameterized constructor an integer variable "x" is passed in the constructor parameter and inside a constructor parameter value is print. Inside the default constructor, a print function (cout) is used that print message "Hello!".
In the main method, a class "TestClass" object is created that is "test" when a class object is created it automatically called a default constructor that's why the output to this code is "Hello!".
