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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.
In class-based programming, downcasting, or type refinement, is the act of casting a base or parent class reference, to a more restricted derived class reference. [1] This is only allowable if the object is already an instance of the derived class, and so this conversion is inherently fallible.
However, a finalizer may create new references to an object, requiring object resurrection to prevent a dangling reference. Wild pointers, also called uninitialized pointers, arise when a pointer is used prior to initialization to some known state, which is possible in some programming languages.
In computing, a null pointer or null reference is a value saved for indicating that the pointer or reference does not refer to a valid object. Programs routinely use null pointers to represent conditions such as the end of a list of unknown length or the failure to perform some action; this use of null pointers can be compared to nullable types ...
The dynamic_cast operator in C++ is used for downcasting a reference or pointer to a more specific type in the class hierarchy. Unlike the static_cast, the target of the dynamic_cast must be a pointer or reference to class. Unlike static_cast and C-style typecast (where type check occurs while compiling), a type safety check is performed at ...
Some programming languages allow a program to operate differently or even have a different control flow from the source code, as long as it exhibits the same user-visible side effects, if undefined behavior never happens during program execution. Undefined behavior is the name of a list of conditions that the program must not meet.
However, more often it is taken to refer to the actual use of an entity before any declaration; that is, the first reference to second in the code above is a forward reference. [2] [3] Thus, we may say that because forward declarations are mandatory in Pascal, forward references are prohibited. An example of (valid) forward reference in C++:
C++ also supports another form of reference, quite different from a pointer, called simply a reference or reference type. Pointer arithmetic , that is, the ability to modify a pointer's target address with arithmetic operations (as well as magnitude comparisons), is restricted by the language standard to remain within the bounds of a single ...