The 'if' statement in C++ is used to make a single conditional decision. It allows you to execute a block of code only if a specified condition is true. This is fundamental for controlling the flow of your program based on conditions.

The 'if-else' statement in C++ is used when you have multiple conditions to test sequentially. It allows you to define different blocks of code to execute for different conditions, providing a structured way to handle multiple possibilities.

Yes, for both. In C++, you can use default arguments for both member methods of a class and standalone (non-member) functions. Default arguments provide flexibility when calling functions or methods by allowing you to omit some arguments if they have defaults defined.

The -> (Arrow) operator is used in C++ to access members of an object or struct through a pointer. For instance, if you have a pointer to a struct ptr and want to access its member x, you can do so using ptr->x.

John wrote the function implementation within the header file. The function implementation contains the actual logic and code that defines how the function performs its task. Writing the entire logic in the header file is not a typical practice and may lead to code organization issues.

Functions in C++ are declared by specifying their return type, followed by the function name and parameters enclosed in parentheses. The correct way to declare a function that takes two integers and returns their sum is by declaring the return type as int and specifying the parameters with commas in between. So, the correct declaration is int sum(int a, int b).

The '__forceinline' keyword is a directive to the compiler that strongly enforces inlining of the function, even if the compiler would not typically inline it based on its heuristics. This keyword provides a more forceful hint to the compiler compared to the 'inline' keyword, ensuring that the function is inlined whenever possible.

Inline functions are expanded at the calling point. When you use the inline keyword, the compiler replaces the function call with the actual function code at the location where the function is called, reducing the overhead of a traditional function call.

The possible reason for Maria's function sometimes using the default value and other times using the value she provides is an Incorrect Function Call. If she calls the function without providing an argument for the parameter with the default value, it will use the default value. However, if she explicitly provides an argument, the provided value will be used.

When a function calls itself as its last operation before returning, it's called 'tail recursion.' Tail recursion is often optimized by compilers, making it an efficient way to implement certain algorithms, like calculating factorials or traversing data structures.