What differentiation between GetMessageA and GetMessageW function?

Question

I am learning programming Window GUI. I don't know differentiation between 2 function GetMessageA and GetMessageW. I saw the GetMessage function have not any parameters involve to ANSI or Unicode.

Answer 1

All older Win32 calls that involve strings are actually macros that expand to either a Unicode version or an ANSI version, based upon the "Character Set" property of the project.

GetMessage(...) will map to either GetMessageA(...) or GetMessageW(...) where the "A" version will handle messages that involve strings as ANSI formatted text and the "W" version will use UTF-16.