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A program can convert a pointer to any type of data (except a function pointer) to a pointer to void and back to the original type without losing information, which makes these pointers useful for polymorphic functions. The C language standard does not guarantee that the different pointer types have the same size or alignment.
In most programming languages, functions may take one or more arguments. Usually, each argument must be specified in full (this is the case in the C programming language [1]). Later languages (for example, in C++) allow the programmer to specify default arguments that always have a value, even if one is not specified when calling the function.
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, a parameter is a type, and an argument is an instance.
The latter form was introduced to avoid confusion, [3] since a type parameter need not be a class until C++20. (It can be a basic type such as int or double.) For example, the C++ Standard Library contains the function template max(x, y) which returns the larger of x and y. That function template could be defined like this:
Without named parameters, optional parameters can only appear at the end of the parameter list, since there is no other way to determine which values have been omitted. In languages that support named optional parameters, however, programs may supply any subset of the available parameters, and the names are used to determine which values have ...
stdarg.h is a header in the C standard library of the C programming language that allows functions to accept an indefinite number of arguments. [1] It provides facilities for stepping through a list of function arguments of unknown number and type. C++ provides this functionality in the header cstdarg.
In C, all subroutines have function definitions (procedures being void functions) and type definitions use the keyword typedef. Both languages use a mix of keywords and punctuation for definitions of complex types; for instance, arrays are defined by the keyword array in Pascal and by punctuation in C, while enumerations are defined by the ...
In computer programming, a function object [a] is a construct allowing an object to be invoked or called as if it were an ordinary function, usually with the same syntax (a function parameter that can also be a function). In some languages, particularly C++, function objects are often called functors (not related to the functional programming ...