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Call by reference (or pass by reference) is an evaluation strategy where a parameter is bound to an implicit reference to the variable used as argument, rather than a copy of its value. This typically means that the function can modify (i.e., assign to) the variable used as argument—something that will be seen by its caller. Call by reference ...
The specification for pass-by-reference or pass-by-value would be made in the function declaration and/or definition. Parameters appear in procedure definitions; arguments appear in procedure calls. In the function definition f(x) = x*x the variable x is a parameter; in the function call f(2) the value 2 is the argument of the function. Loosely ...
Pointers are used to pass parameters by reference. This is useful if the programmer wants a function's modifications to a parameter to be visible to the function's caller. This is also useful for returning multiple values from a function. Pointers can also be used to allocate and deallocate dynamic variables and arrays in memory. Since a ...
This function requires C++ – would not compile as C. It has the same behavior as the preceding example but passes the actual parameter by reference rather than passing its address. A call such as addTwo(v) does not include an ampersand since the compiler handles passing by reference without syntax in the call.
Even when function arguments are passed using "call by value" semantics (which is always the case in Java, and is the case by default in C#), a value of a reference type is intrinsically a reference; so if a parameter belongs to a reference type, the resulting behavior bears some resemblance to "call by reference" semantics.
In Common Lisp, the identifier of a function in the function namespace cannot be used as a reference to a first-class value. The special operator function must be used to retrieve the function as a value: (function foo) evaluates to a function object. #'foo exists as a shorthand notation. To apply such a function object, one must use the ...
In C++ and PHP, unary prefix & before a formal parameter of a function denotes pass-by-reference. [26] [27] In Pascal, the & as the first character of an identifier prevents the compiler from treating it as a keyword, thus escaping it. In Fortran, the ampersand forces the compiler to treat two lines as one. This is accomplished by placing an ...
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