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In C++ pointers to non-static members of a class can be defined. If a class C has a member T a then &C::a is a pointer to the member a of type T C::*. This member can be an object or a function. [16] They can be used on the right-hand side of operators .* and ->* to access the corresponding member.
In the C++ programming language, a reference is a simple reference datatype that is less powerful but safer than the pointer type inherited from C.The name C++ reference may cause confusion, as in computer science a reference is a general concept datatype, with pointers and C++ references being specific reference datatype implementations.
A class in C++ is a user-defined type or data structure declared with any of the keywords class, struct or union (the first two are collectively referred to as non-union classes) that has data and functions (also called member variables and member functions) as its members whose access is governed by the three access specifiers private, protected or public.
Wrapper references are similar to normal references (‘&’) of the C++ language. To obtain a wrapper reference from any object the function template ref is used (for a constant reference cref is used). Wrapper references are useful above all for function templates, where references to parameters rather than copies are needed:
C++ includes support for object-oriented programming, so classes can have methods (usually referred to as member functions). Non-static member functions (instance methods) have an implicit parameter (the this pointer) which is the pointer to the object it is operating on, so the type of the object must be included as part of the type of the ...
In addition, a (non-static) member-function can be declared as const. In this case, the this pointer inside such a function is of type object_type const * rather than merely of type object_type *. [2] This means that non-const functions for this object cannot be called from inside such a function, nor can member variables be modified.
As such, the compiler must also generate "hidden" code in the constructors of each class to initialize a new object's virtual table pointer to the address of its class's virtual method table. Many compilers place the virtual table pointer as the last member of the object; other compilers place it as the first; portable source code works either ...
In class-based, object-oriented programming, an instance variable is a variable defined in a class (i.e., a member variable), for which each instantiated object of the class has a separate copy, or instance. [1] [2] An instance variable has similarities with a class variable, [3] but is non-static.