The basic way to support both ASCII and Unicode:

By useing #include <tchar.h>, you can support both ASCII and Unicode in your program. The tchar.h header file, defined both way to conduct two kinds of character. Use the macro “_UNICODE” to control if use Unicode.

Use TCHAR to designate a variable, and call the functions such as _tcscpy, _tcschr, _tcscmp, _tcsclen and so on, the operation would switch according to if defined “_UNICODE”.

When there is a letter “T” in the character variable, such as TCHAR, or LPCTSTR, this variety supports both ASCII and Unicode. If _UNICODE is defined, then TCHAR stands for wchar_t, or else the TCHAR stands for char.

Use the L prefix before a character or string constant to designate the wide-character-type constant.

By the way, the wchar_t is the same as unsigned short.

Type Name	Bytes	Other Names	Range of Values
Int	4	signed	–2,147,483,648 to 2,147,483,647
__int8	1	char, signed char	–128 to 127
__int16	2	short, short int, signed short int	–32,768 to 32,767
__int32	4	signed, signed int, int	–2,147,483,648 to 2,147,483,647
__int64	8	long long, signed long long	–9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
Bool	1	none	false or true
Char	1	none	–128 to 127
Short	2	short int, signed short int	–32,768 to 32,767
Long	4	long int, signed long int	–2,147,483,648 to 2,147,483,647
long long	8	none (but equivalent to __int64)	–9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
Enum	4	none	Same as int
Float	4	none	3.4E +/- 38 (7 digits)
Double	8	none	1.7E +/- 308 (15 digits)
Long double	same as double	none	same as double
wchar_t	2	__wchar_t	0 to 65,535