That is telling you that you need to use Sqr<int>::doIt.
Well actually, as you know, the compiler can figure that out. The problem lies in that the class function is not static or the OP isn't calling the function on an actual instance of the object.
Originally Posted by Adak
io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
Originally Posted by Salem
You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.
Outside of your DOS world, your header file is meaningless.