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void (C++)

2011-06-03 10:31  Rollen Holt  阅读(220)  评论(0编辑  收藏  举报

When used as a function return type, the void keyword specifies that the function does not return a value. When used for a function's parameter list, void specifies that the function takes no parameters. When used in the declaration of a pointer, void specifies that the pointer is "universal."

If a pointer's type is void *, the pointer can point to any variable that is not declared with the const or volatile keyword. A void pointer cannot be dereferenced unless it is cast to another type. A void pointer can be converted into any other type of data pointer.

A void pointer can point to a function, but not to a class member in C++.

You cannot declare a variable of type void.

Code:
  1. // void.cpp  
  2. void vobject;   // C2182  
  3. void *pv;   // okay  
  4. int *pint; int i;  
  5. int main() {  
  6.    pv = &i;  
  7.    // Cast optional in C required in C++  
  8.    pint = (int *)pv;  
  9. }