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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.
Many languages have explicit pointers or references. Reference types differ from these in that the entities they refer to are always accessed via references; for example, whereas in C++ it's possible to have either a std:: string and a std:: string *, where the former is a mutable string and the latter is an explicit pointer to a mutable string (unless it's a null pointer), in Java it is only ...
On many common platforms, this use of pointer punning can create problems if different pointers are aligned in machine-specific ways. Furthermore, pointers of different sizes can alias accesses to the same memory, causing problems that are unchecked by the compiler. Even when data size and pointer representation match, however, compilers can ...
In C++, classes can be forward-declared if you only need to use the pointer-to-that-class type (since all object pointers are the same size, and this is what the compiler cares about). This is especially useful inside class definitions, e.g. if a class contains a member that is a pointer (or a reference) to another class.
The C and C++ syntax given above is the canonical one used in all the textbooks - but it's difficult to read and explain. Even the above typedef examples use this syntax. However, every C and C++ compiler supports a more clear and concise mechanism to declare function pointers: use typedef, but don't store
If there are base class methods overridden by the derived class, the method actually called by such a reference or pointer can be bound (linked) either "early" (by the compiler), according to the declared type of the pointer or reference, or "late" (i.e., by the runtime system of the language), according to the actual type of the object is ...
Prevention of illegal operations. For example, a type system can reject the expression 3 / "Hello, World" as invalid, because the division operator is not defined for a string divisor. Memory safety. Type systems can prevent wild pointers that could otherwise arise from a pointer to one type of object being treated as a pointer to another type.
class name definition «inheriting from parentclass». «interfaces: interfaces.» method_and_field_declarations endclass. class name implementation. method_implementations endclass. interface name . members endinterface.