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New is used to dynamically allocate memory in C++. It will also call the default constructor of a class that is created with it.

int *array; // First declare a pointer

array = new int [5] // Allocate enough memory for a 5 element int array

// To deallocate your memory when you are finished with it, you must call delete on your pointer

delete[] array;

myClassType *mct = new myClassType; // example for class

...

delete mct; // class delete

The virtual keyword means that the class has a static virtual table (vtable) containing function pointers for each type of the class. This enables polymorphism by allowing a pointer to the base class to be assigned an address of any instance of the class in the hierarchy, and then invoking a method through that pointer - which will properly choose the correct method for that class type. Virtual also ensures that the constructors and destructors are invoked in the correct order.

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Q: What is the use of keyword virtual?
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The lazy way is to use a dynamic cast. The correct way is to use virtual functions in the base class. That way you don't ever need to know the derived type -- it simply does what is expected of it.


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Related questions

What is the use of keyword new used in AWT programming?

what is the use of new keyword in awt programming


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