The _T is a macro provided by TCHAR.H for unicode/multilingual support. If you go to the project settings->general tab->Character set you will have that to "not set" setting. That macro allows you to use the other choices being unicode and multi-byte character sets making your code work multilingual like in chineese windows. For you in ascii mode the macro actually does nothing (which you worked out) but if you select the other modes you will see you will get an error on every static text the _T tells the compiler to make the string in the correct mode and removes the error. Being a commercial programmer and as Microsoft has made it so easy for doing it we generally try and use the multilingual code calls since Visual Studio 2013. This became almost compulsory when trying to write true 64 bit applications. The default setting of an empty project is actually to set for unicode character set. Essentially TCHAR becomes a replacement for the standard char and its size varies in the compilation modes. They provide new string functions that match the old string functions in TCHAR.H but have different code for the different modes. Lets give you an example strlen becomes _tcslen those calls work identical the difference being _tcslen will work in any language mode compilation, while strlen will only work in language "not set" mode like you have. Here is the link to what is going on from MSDN strlen, wcslen, _mbslen, _mbslen_l, _mbstrlen, _mbstrlen_l[^] This code is designed specifically for windows (it uses the Win32 API), it is not general in nature like that could work on linux so there is no reason to write generically but we should try and cover the different modes of windows compilation, especially as it is easy. So for me the changes are just habit. There is a funny part of this that so many of us are writing in that style that the linux community is having issues trying to port our code. So if writing general code I would probably try to avoid this style of programming.
In vino veritas
