C++ is a powerful programming language known for its efficiency and versatility. One of the features that sets it apart from other languages is the ability to obtain type information at runtime, known as Runtime Type Information (RTTI). RTTI allows you to query and manipulate the type of an object at runtime, providing flexibility and dynamic behavior in your code.

What is RTTI?

RTTI, as the name suggests, is a mechanism that enables a program to determine the type of an object during runtime. It allows you to perform type-related operations such as type casting and type checking dynamically, without needing to know the type at compile-time. This is particularly useful in situations where you need to handle objects of different types, but the specific type is not known until runtime.

The ‘typeid’ Operator

In C++, the typeid operator is used to obtain the RTTI of an object. It returns an object of type std::type_info that contains the type information. Here’s an example:

#include <iostream>
#include <typeinfo>

class Base {
    // Class definition
};

class Derived : public Base {
    // Class definition
};

int main() {
    Base* basePtr = new Derived();

    if (typeid(*basePtr) == typeid(Derived)) {
        std::cout << "Derived class object" << std::endl;
    } else if (typeid(*basePtr) == typeid(Base)) {
        std::cout << "Base class object" << std::endl;
    }

    delete basePtr;
    return 0;
}

In the code above, we have a Base class and a Derived class inheriting from Base. We create a pointer of type Base and assign it a new instance of Derived. By using the typeid operator, we can check the actual type of the object pointed to by basePtr and perform different operations based on that.

Working with ‘dynamic_cast’

Apart from type checking, you can also perform type casting using dynamic_cast. It is a C++ operator used for converting pointers or references to base classes into pointers or references of derived classes. If the conversion is not possible, dynamic_cast returns a null pointer. Here’s an example:

Derived* derivedPtr = dynamic_cast<Derived*>(basePtr);
if (derivedPtr != nullptr) {
    std::cout << "Successfully cast to Derived class" << std::endl;
} else {
    std::cout << "Failed to cast to Derived class" << std::endl;
}

In the code snippet above, we attempt to cast basePtr, which is of type Base, to a pointer of type Derived using dynamic_cast. If the cast is successful, the resulting pointer will be non-null, indicating a successful conversion.

Conclusion

Runtime Type Information (RTTI) in C++ allows you to obtain type information at runtime, providing you with flexibility and dynamic behavior in your code. By using the typeid operator, you can check the type of an object during runtime. Additionally, dynamic_cast enables you to perform type casting dynamically, converting pointers or references to base classes into pointers or references of derived classes. These features empower C++ developers to handle objects of different types in a more versatile manner.

#C++ #RTTI