Data Types

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This topic lists the data types most commonly used in the Microsoft Foundation Class Library. Most of the data types are exactly the same as those in the Windows Software Development Kit (SDK), while others are unique to MFC.

Commonly used Windows SDK and MFC data types are as follows:

  • BOOL   A Boolean value.

  • BSTR   A 32-bit character pointer.

  • BYTE   An 8-bit integer that is not signed.

  • COLORREF   A 32-bit value used as a color value.

  • DWORD   A 32-bit unsigned integer or the address of a segment and its associated offset.

  • LONG   A 32-bit signed integer.

  • LPARAM   A 32-bit value passed as a parameter to a window procedure or callback function.

  • LPCSTR   A 32-bit pointer to a constant character string.

  • LPSTR   A 32-bit pointer to a character string.

  • LPCTSTR   A 32-bit pointer to a constant character string that is portable for Unicode and DBCS.

  • LPTSTR   A 32-bit pointer to a character string that is portable for Unicode and DBCS.

  • LPVOID   A 32-bit pointer to an unspecified type.

  • LRESULT   A 32-bit value returned from a window procedure or callback function.

  • UINT   A 16-bit unsigned integer on Windows versions 3.0 and 3.1; a 32-bit unsigned integer on Win32.

  • WNDPROC   A 32-bit pointer to a window procedure.

  • WORD   A 16-bit unsigned integer.

  • WPARAM   A value passed as a parameter to a window procedure or callback function: 16 bits on Windows versions 3.0 and 3.1; 32 bits on Win32.

Data types unique to the Microsoft Foundation Class Library include the following:

  • POSITION   A value used to denote the position of an element in a collection; used by MFC collection classes.

  • LPCRECT   A 32-bit pointer to a constant (nonmodifiable) RECT structure.