Although most platforms supported by provide a definition of wchar_t in a system include file, not all do. Those that do use definitions of different lengths; some provide definitions that are not suitable for all the character codes supported by . Therefore, takes considerable care to make sure it uses a suitable definition of wchar_t on each supported platform.

It is essential to make sure your application is using the same definition of wchar_t as on each platform your application supports. To make this easier, supplies the include filepro_wchar_t.h. This file ensures that, if a definition of wchar_t.h has not already been made in an earlier include file, one is provided that is consistent with the definition of the type. Because this file is included by the file ProToolkit.h, you should include ProToolkit.h as the very first include file in each source file.