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An output parameter, also known as an out parameter or return parameter, is a parameter used for output, rather than the more usual use for input. Using call by reference parameters, or call by value parameters where the value is a reference, as output parameters is an idiom in some languages, notably C and C++, [ b ] while other languages have ...
Manipulation of these parameters can be done by using the routines in the standard library header < stdarg. h >. In C++, the return type can also follow the parameter list, which is referred to as a trailing return type. The difference is only syntactic; in either case, the resulting signature is identical:
If the expression e refers to a variable in local or namespace scope, a static member variable or a function parameter, then the result is that variable's or parameter's declared type; Otherwise, if e is an lvalue, decltype(e) is T&, where T is the type of e; if e is an xvalue, the result is T&&; otherwise, e is a prvalue and the result is T.
The term "function prototype" is particularly used in the context of the programming languages C and C++ where placing forward declarations of functions in header files allows for splitting a program into translation units, i.e. into parts that a compiler can separately translate into object files, to be combined by a linker into an executable ...
For example, += and -= are often called plus equal(s) and minus equal(s), instead of the more verbose "assignment by addition" and "assignment by subtraction". The binding of operators in C and C++ is specified (in the corresponding Standards) by a factored language grammar, rather than a precedence table. This creates some subtle conflicts.
In C and C++, volatile is a type qualifier, like const, and is a part of a type (e.g. the type of a variable or field). The behavior of the volatile keyword in C and C++ is sometimes given in terms of suppressing optimizations of an optimizing compiler: 1- don't remove existing volatile reads and writes, 2- don't add new volatile reads and writes, and 3- don't reorder volatile reads and writes.
Because default arguments' values are "filled in" at the call site rather than in the body of the function being called, virtual functions take their default argument values from the static type of the pointer or reference through which the call is made, rather than from the dynamic type of the object supplying the virtual function's body.
In object-oriented programming languages, it is possible to use method chaining to simulate named parameters, as a form of fluent interface. Each named-parameter argument is replaced with a method on an "arguments" object that modifies and then returns the object. In C++, this is termed the named parameter idiom. [17]