How Can I Determine the Type of an Object in C at Runtime?

Determining the Type of an Object in C

In C , it's often necessary to ascertain the type of an object passed as a parameter. This scenario arises when overriding functions that accept objects of a specific type and subsequently require access to specialized functionality available only in derived classes.

To address this challenge, C provides the dynamic_cast operator, which offers a solution to this problem. Dynamic casting allows for the safe casting of a pointer or reference from one type to another at runtime.

Implementation:

The dynamic_cast operator can be used in two forms:

• Casting to References:

  TYPE& dynamic_cast<TYPE&>(object);

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• Casting to Pointers:

  TYPE* dynamic_cast<TYPE*>(object);

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How it Works:

The dynamic_cast operator performs a runtime check to ensure the validity of the cast. If successful, it returns a reference or pointer to the derived type. Otherwise, if the cast is not valid, it returns nullptr or throws a bad_cast exception in the case of reference casting.

Requirement for Dynamic Casting:

It's important to note that dynamic_cast requires the presence of at least one virtual function in the base class for it to function correctly. This is because C uses the concept of Run-time Type Information (RTTI) to determine the type of an object at runtime. RTTI is available only for polymorphic classes, which are classes with at least one virtual method.

Additional Resources:

• Wikipedia: Run-time Type Information:
  https://en.wikipedia.org/wiki/Run-time_type_information

Conclusion:

Dynamic casting provides a straightforward and efficient method for determining the type of an object in C . It allows code to safely handle objects of different types and access type-specific functionality, ensuring safe and flexible code execution.

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