单字符 和 宽字符

#define PI   3.14
//产生新类型
typedef 3.14 PI
单字符，一个字节存储，宽字符，二个字节存储。
sizeof(L"abc")=8
size("abc")=4
typedef unsigned short wchar_t;
char
typedef  wchar_t WCHAR;
typedef  char CHAR;
WCHAR* p = L"Hello";
CHAR* = "Hello";
typedef  const CHAR* CSTR;
typedef  const WCHAR* CWSTR;
typedef  const CHAR* LPCSTR;
LPCSTR = PCSTR
单字符版本
宽字符版本
#ifdef _UNICODE
#define TEXT(x) L##x => L"x"
#else
#define TEXT(x) x
#endif
#define _T(x) TEXT(x)
SetWindowText(TEXT("QQ"))
SetWindowText(_T("QQ"))
#ifdef _UNICODE
#define PTSTR PWSTR
#else
#define PTSTR PSTR
#endif
#ifdef _UNICODE
#define PCTSTR PCWSTR
#else
#define PCTSTR PCSTR
#endif
#ifdef _UNICODE
#define _tWinMain wWinMain
#else
#define _tWinMain WinMain
#endif