When a function in C++ is declared with a return type other than void, it's a promise that the function will return a value of that type. If the function does not return any value, it will lead to a compilation error because the contract of returning a value (as per its declaration) is violated.

Single inheritance restricts a derived class to inherit from only one base class. While C++ supports multiple inheritance, where a class can inherit from more than one class, single inheritance ensures there's a straightforward lineage from the base to the derived class, avoiding complexities and potential ambiguities.

Jumping over the initialization of a variable using the goto statement will result in a compilation error because the compiler will identify it as an attempt to bypass variable initialization.

A switch-case is generally more advantageous for implementing FSM in C++ because it improves readability when dealing with a set of known, discrete values (like states). It's also more performant than a chain of if-else statements in scenarios where there are multiple states.

unique_ptr is a smart pointer that owns a dynamically allocated object exclusively. It ensures that only one unique_ptr can point to the object at a time. If another unique_ptr tries to take ownership, the original will relinquish its hold, ensuring uniqueness.

The new operator in C++ is used to allocate memory on the heap at runtime. When you use new, it returns a pointer to the beginning of the block of memory it allocated. This is essential for dynamic memory management, as it allows more flexible storage allocation during program execution.

Function templates are utilized primarily to enable generic programming, meaning writing code that works for multiple data types without repetition. While they may have indirect effects on execution speed or code size, using them to group unrelated types doesn't align with their primary purpose.

An abstract class in C++ is a class that cannot be instantiated, meaning objects of the class cannot be created directly. Abstract classes are intended to be inherited by other classes.

The unsigned char data type in C++ uses 8 bits (1 byte) for storage. This means it can store values ranging from 0 to 2^8-1, which is 0 to 255.

In C++, switch-case constructs don't support floating-point types for case values. This means you can't use float or double values as cases. On the other hand, if-else structures can easily handle conditions based on floating-point values.

In C++, any non-zero value is considered as true. The logical NOT (!) operator inverts the truthiness of its operand. So, if applied to a non-zero (true) operand, the output will be false, which is represented as 0.

When any number is bitwise AND-ed with 0, the result is always 0. This is because the AND operation yields 1 only if both bits being compared are 1; otherwise, it yields 0.