A function with a void return type doesn't return any value. It is often used for functions that perform an action but do not need to send a result back to the caller.

Encapsulation is a core concept in object-oriented programming. Its primary purpose in C++ and other OOP languages is to hide the internal representation, or state, of an object from the outside and to bundle the data (attributes) and the methods (functions) that operate on the data into a single unit, thus hiding complexity.

In C++, dynamic memory allocation for objects is achieved using the new operator. Unlike malloc in C, new in C++ initializes the allocated memory.

The "Diamond Problem" arises in object-oriented languages that support multiple inheritance. If a class is derived from two classes that have a common base class, the derived class may inherit the same member more than once.

Function overloading in C++ allows multiple functions with the same name but different parameters (types and/or number). They must be in the same scope. Return type alone cannot be used to distinguish overloaded functions, and both member and non-member functions can be overloaded.

Constructors in C++ cannot be virtual. When creating an instance of a derived class, it's essential to know the exact type of the object being created, so the correct constructor gets called. Making constructors virtual doesn't make sense in the context of object-oriented design, as it would introduce ambiguity in the object creation process.

The failbit is a status flag in C++ streams that indicates a file operation failed. When working with file I/O in C++, it's crucial to check this flag (or use functions like fail()) to determine if a particular operation has encountered an error.

C++ typically handles template instantiation on a per-translation unit basis. This means each translation unit will have its own instance of the template. Linkers are smart enough to discard duplicate instances, ensuring that only one instance remains in the final executable.

The auto keyword for automatic type deduction was introduced in C++11. It allows the compiler to automatically deduce the type of a variable based on its initializer, enhancing code readability and maintainability.

The Command Pattern encapsulates a command request as an object, allowing the parameters to be passed, queued, and executed at a later time. This makes the code modular, maintainable, and ensures decoupling between classes that invoke operations from those that perform operations.