For a recursive function to successfully terminate, it must have a base case. A base case is a condition under which the function stops calling itself and starts returning values. Without a base case, a recursive function would call itself indefinitely, leading to an infinite loop and, in most cases, a stack overflow error.

Overloading refers to defining multiple functions with the same name but different signatures (usually different number or type of parameters). Overriding, on the other hand, is related to inheritance and polymorphism where a derived class provides a specific implementation for a method that is already provided by its base class. In overriding, the method in the derived class should have the same name, return type, and parameters as the method in the base class. The key difference is thus related to polymorphism and inheritance for overriding versus method signature differences for overloading.

The "private" access specifier in C++ restricts access to class members, ensuring they can't be accessed or modified outside the class, thereby maintaining encapsulation and data integrity within the class.

In C++, if a function with a return type other than void does not have a return statement, but throws an exception that exits the function, it's acceptable and will not result in a compilation error.

In the 'try' block, we place the code that might throw an exception. Any exception that occurs inside the 'try' block can be caught by the subsequent 'catch' block, allowing for appropriate error handling.

Operator overloading in C++ allows operators to be redefined and used in a custom manner with user-defined types (like classes). This enhances code readability and allows for more intuitive programming when working with custom data types, making operations feel more natural.

In multi-level inheritance, it's essential to maintain data integrity and manage complexity. This is achieved by encapsulating data at every inheritance level, ensuring that each class exposes only what's necessary to its derived classes. Abstract interfaces further help in defining clear boundaries and interactions between classes.

In C++, there isn't a direct concept of "interfaces" as in some other languages. However, abstract classes with only pure virtual functions can act similarly to interfaces. These ensure abstraction by forcing derived classes to provide concrete implementations, but not all abstractions need to be interfaces.

shared_ptr uses reference counting, which means it keeps a count of the number of shared_ptr objects referring to the same memory location. When this count drops to zero (meaning no shared pointers are referring to the object), the memory is automatically deallocated.

The if-else control structure in C++ provides a way to perform decision-making operations. If the condition inside the 'if' block evaluates to true, the 'if' block of code is executed; otherwise, the 'else' block is executed, if present. It can be used to check multiple conditions in sequence by nesting or using "else if".

The keyword virtual is used in C++ to make a function virtual. When a function is declared as virtual, it can be overridden in any derived class. This allows for dynamic polymorphism, where the decision on which method version to execute is made at runtime based on the object's actual type.

Function overloading allows multiple functions in the same scope to have the same name as long as they have different parameter lists. In C++, the appropriate overloaded function is chosen at compile-time based on the function call's arguments.