wchar

WCHAR is a Windows data type used to represent a single wide character in Windows API strings. It is defined as a typedef of wchar_t in the Windows headers (often in WinNT.h), and is widely used to denote Unicode code units stored as wide characters within Windows applications. The underlying size of WCHAR is platform dependent through wchar_t, but on Windows it is 16 bits, corresponding to UTF-16 code units. As such, a single WCHAR may represent a UTF-16 code unit and, for characters outside the Basic Multilingual Plane, may form surrogate pairs when composing actual code points.

In practice, WCHAR is used for wide-character strings, where arrays of WCHAR hold null-terminated sequences. Literals are created with the L prefix, for example L"Hello", or via the TEXT macro in code designed to compile with or without Unicode support. Windows API functions that operate on wide strings typically carry a W suffix, such as CreateFileW, lstrcmpW, or wprintf, and these functions expect pointers to WCHAR arrays.

WCHAR is conceptually aligned with the C standard type wchar_t, and in Windows they are effectively the same type. However, wchar_t is a standard C/C++ type whose size is implementation-defined on non-Windows platforms, whereas WCHAR is a Windows-specific alias used for consistency within the Windows API. For portability, developers may choose to use wchar_t directly or consider other encodings, such as char16_t, depending on the target platform.

Because Windows uses UTF-16 encoding for wide strings, supplementary characters are represented using surrogate pairs. Converting between UTF-8/ANSI and UTF-16 typically involves Windows API functions like MultiByteToWideChar and WideCharToMultiByte.