Is Checking for Null Pointers in Member Functions Necessary and Reliable in C Multithreaded Applications?

Checking for Null Pointers in Member Functions

Question:

In a multithreaded application, consider a class with a member function. Is it valid to check if the this pointer is nullptr within the function and return an error code if it is?

Answer:

In standard C , accessing a null pointer is undefined behavior. Therefore, checking if this is nullptr and returning an error code is not necessary and can lead to non-standard behavior.

Additional Considerations:

• Some implementations, such as VC and MFC, allow this to be checked for nullptr. Однако, such implementations are non-standard and may lead to unreliable code.
• Inserting such checks may be useful for debugging purposes, but assert statements are a more appropriate choice for this.
• Checking if this is nullptr does not necessarily indicate that the object has been deleted. It could simply mean that a null pointer was used to call the method or obtain the this reference.

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