What does void mean in C, C++, and C#?

c# c++ c language-design terminology
Nick Katsivelos picture Nick Katsivelos · Jun 25, 2009 · Viewed 375.4k times · Source

Looking to get the fundamentals on where the term "void" comes from, and why it is called void. The intention of the question is to assist someone who has no C experience, and is suddenly looking at a C-based codebase.

Answer

Gerald picture Gerald · Jun 25, 2009

Basically it means "nothing" or "no type"

There are 3 basic ways that void is used:

  1. Function argument: int myFunc(void) -- the function takes nothing.

  2. Function return value: void myFunc(int) -- the function returns nothing

  3. Generic data pointer: void* data -- 'data' is a pointer to data of unknown type, and cannot be dereferenced

Note: the void in a function argument is optional in C++, so int myFunc() is exactly the same as int myFunc(void), and it is left out completely in C#. It is always required for a return value.

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