http://stackoverflow.com/a/2849040
May help you.
1) Windows console uses ASCII by default and doesn't handle unicode characters.
2) Default font doesn't have support for unicode either. (Change it to something non raster)
On Windows/Visual Studio (which appears to be what you're using, based on the warning message), the simplest solution, I believe, is to enable wide character output:
Thanks, but umm. for the "L" I don't think I really need it because it usually gives me no warning, in my messagebox test program, when I add L, it doesn't work, but when I remove it it does but thanks!