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In C++11 the following function declaration:
int f(void); means the same as:
int f(); A parameter list consisting of a single unnamed parameter of non-dependent type void is equivalent to an empty parameter list.
I get the (perhaps false) impression this is an old feature, perhaps inherited from C?
Does anyone know the history or rationale behind this way to declare a function with no parameters?
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In computer programming, when void is used as a function return type, it indicates that the function does not return a value. When void appears in a pointer declaration, it specifies that the pointer is universal. When used in a function's parameter list, void indicates that the function takes no parameters.
In C, an empty parameter list means that the number and type of the function arguments are unknown. Example: int f(); // means int f(void) in C++ // int f( unknown ) in C. In C, it makes sense to avoid that undesirable "unknown" meaning. In C++, it's superfluous.
Declaration void f(void); means that f does not take any parameters. Declaration void f(); means that function f may or may not have parameters, and if it does, we don't know what kind of parameters those are, or how many there is of them.
A void function with value parameters are declared by enclosing the list of types for the parameter list in the parentheses. To activate a void function with value parameters, we specify the name of the function and provide the actual arguments enclosed in parentheses.
In C++ they both mean the same thing.
In C f(void) is different from f(), becuse f() means "unspecified parameters" - you can legally pass anything (whether the function at receiving the data is happy about that or not is another matter).
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