In C, the statement int a; when made at file scope, is a declaration and a tentative definition. You can have as many tentative definitions as you want, as long as they all match each other. If a definition (with an initializer) appears before the end of the translation unit, the variable will be initialized … Read more
Overriding essentially means that either the Base class method or the Derived class method will be called at run-time depending on the actual object pointed by the pointer. It implies that: i.e: Every place where the Base class method can be called can be replaced by call to Derived class method without any change to … Read more
This problem is caused when including <windows.h> before <winsock2.h>. Try arrange your include list that <windows.h> is included after <winsock2.h> or define _WINSOCKAPI_ first: #define _WINSOCKAPI_ // stops windows.h including winsock.h #include <windows.h> // … #include “MyClass.h” // Which includes <winsock2.h> See also this.