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Since C++11, the C++ standard library also provides smart pointers (unique_ptr, shared_ptr and weak_ptr) which can be used in some situations as a safer alternative to primitive C pointers. C++ also supports another form of reference, quite different from a pointer, called simply a reference or reference type.
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 ...
The reference to the object is passed as a hidden argument, usually accessible from within the method as this. A parameter called by reference is syntactic sugar for technically passing a pointer as the parameter, but syntactically handling it as the variable itself, to avoid constant pointer de-referencing in the code inside the function.
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 reference is an abstract data type and may be implemented in many ways. Typically, a reference refers to data stored in memory on a given system, and its internal value is the memory address of the data, i.e. a reference is implemented as a pointer. For this reason a reference is often said to "point to" the data.
Objects that are shared but not owned can be accessed via a reference, raw pointer, or iterator (a conceptual generalisation of pointers). However, by the same token, C++ provides native ways for users to opt-into such functionality: C++11 provides reference counted smart pointers, via the std::shared_ptr class, enabling automatic shared memory ...
A function pointer, also called a subroutine pointer or procedure pointer, is a pointer referencing executable code, rather than data. Dereferencing the function pointer yields the referenced function , which can be invoked and passed arguments just as in a normal function call.
In C and C++, constructs such as pointer type conversion and union — C++ adds reference type conversion and reinterpret_cast to this list — are provided in order to permit many kinds of type punning, although some kinds are not actually supported by the standard language.