Microsoft Visual Studio and Unicode

If you are using Microsoft Visual Studio 200x, and 2010, please note that the default character set for new Win32 or similar projects created with Visual Studio is Unicode. Therefore it is always best to use DTWAIN32U.DLL or DTWAIN64U.DLL for these projects.

You can still use DTWAIN32.DLL and DTWAIN64.DLL, however you will need to make sure that all of the strings you send to the string-related DTWAIN functions are ANSI (8-bit) character strings (char is the base type for ANSI strings/arrays, as opposed to TCHAR).