#note needs editing, possibly redundant

void C++

1. 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.”
2. 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.
3. A void pointer can point to a function, but not to a class member in C++.

void vobject;   // C2182  
void *pv;   // okay  
int *pint; int i;  
int main() {  
pv = &i;  
   // Cast optional in C required in C++  
pint = (int *)pv;

Volatile C++

1. A type qualifier that you can use to declare that an object can be modified in the program by the hardware.

volatile declarator ;

virtual C++

1. The virtual keyword declares a virtual function or a virtual base class.

virtual [type-specifiers] member-function-declarator  
virtual [access-specifier] base-class-name

Parameters

1. type-specifiers Specifies the return type of the virtual member function.
2. member-function-declarator Declares a member function.
3. access-specifier Defines the level of access to the base class, public, protected or private. Can appear before or after the virtual keyword.
4. base-class-name Identifies a previously declared class type

this pointer

1. The this pointer is a pointer accessible only within the nonstatic member functions of a class, struct, or union type. It points to the object for which the member function is called. Static member functions do not have a this pointer.

this->member-identifier