As mentioned, non-ASCII characters are allowed in source files, but they will be interpreted according to your current locale settings (in Windows terms, the "ANSI codepage"). But copy that file to another machine and who knows what might happen. One safe way to deal with this, as others have mentioned, is to use Unicode escapes for non-ASCII characters. Another is to explicitly set the character encoding for your source file with the encoding pragma. But be aware that this pragma has some caveats so read its documentation carefully.