windows.h
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<windows.h> is a source code header file that Microsoft provides for the development of programs that access the Windows API (WinAPI) via C language. It declares the WinAPI functions, associated data types and common macros.
Access to WinAPI can be enabled for a C or C++ program by including it into a source file:
#include <windows.h>
Also, the executable must be linked to each static library that either contains the function code or more commonly defines runtime, dynamic linking to a system dynamic link library (DLL). Generally, for functions in a DLL named like Abc.dll, the program must be linked to a library named like Abc.lib. For MinGW, the library name is like libAbc.dll.a.
<windows.h> is a large header file and is often consumed as a precompiled header[1]; however, when imported as a header unit (import <windows.h>;), it is prone to bugs and macro collisions (as <windows.h> defines function-like macros like min() and max() which clash with the standard library).
Included header files
[edit]Including <windows.h> results in including various other header files that are included directly or indirectly by <windows.h>. Many of these header files cannot be included on their own due to dependencies between the various header files.
Notable included header files:
Standard C
[edit]| Name | Description |
|---|---|
<ctype.h> | character classification |
<stdarg.h> | variable-argument function support |
<string.h> | string and buffer manipulation |
Basic
[edit]| Name | Description |
|---|---|
<basetsd.h> | various types[2] |
<guiddef.h> | the GUID[3] |
<imm.h> | Input Method Editor (IME) |
<winbase.h> | kernel32.dll: kernel services; advapi32.dll: kernel services (e.g. CreateProcessAsUser() function), access control (e.g. AdjustTokenGroups() function). |
<wincon.h> | console services |
<windef.h> | various macros and types |
<winerror.h> | error codes[4] |
<wingdi.h> | Graphics Device Interface (GDI)[5] |
<winnetwk.h> | Windows Networking (WNet)[6] |
<winnls.h> | Native Language Support (NLS) |
<winnt.h> | various macros and types (for Windows NT)[7] |
<winreg.h> | Windows registry[8] |
<winsvc.h> | Windows services and the Service Control Manager (SCM) |
<winuser.h> | Calls on user32.dll for user services, inline resource macro (e.g. MAKEINTRESOURCE macro[9]), inline dialog macro(e.g. DialogBox function[10]).[11] |
<winver.h> | version information[12] |
Extra
[edit]| Name | Description |
|---|---|
<cderr.h> | CommDlgExtendedError function error codes |
<commldg.h> | Common Dialog Boxes |
<dde.h> | DDE (Dynamic Data Exchange) |
<ddeml.h> | DDE Management Library |
<dlgs.h> | various constants for Common Dialog Boxes |
<lzexpand.h> | LZ (Lempel-Ziv) compression/decompression |
<mmsystem.h> | Windows Multimedia |
<nb30.h> | NetBIOS |
<rpc.h> | RPC (Remote procedure call) |
<shellapi.h> | Windows Shell API |
<wincrypt.h> | Cryptographic API |
<winperf.h> | Performance monitoring |
<winresrc.h> | used in resources |
<winsock.h> | Winsock (Windows Sockets), version 1.1 |
<winspool.h> | Print Spooler |
<winbgim.h> | Standard graphics library |
OLE and COM
[edit]| Name | Description |
|---|---|
<ole2.h> | OLE (Object Linking and Embedding) |
<objbase.h> | COM (Component Object Model) |
<oleauto.h> | OLE Automation |
<oletlid.h> | various GUID definitions |
Macros
[edit]Several macros affect the definitions made by <windows.h> and the files it includes.
UNICODE; when defined, this causes the generic text datatypeTCHARto be a synonym of WCHAR instead of CHAR,[2] and all type-generic API functions and messages that work with text will be defined to the -W versions instead of the -A versions. It is similar to the windows C runtime's_UNICODEmacro.RC_INVOKEDdefined when the resource compiler (RC.EXE) is in use instead of a C compiler.WINVERused to enable features only available in newer operating systems. Define it to0x0501for Windows XP, and0x0600for Windows Vista.WIN32_LEAN_AND_MEANused to reduce the size of the header files and speed up compilation. Excludes things like cryptography, DDE, RPC, the Windows Shell and Winsock.
Other languages
[edit]Microsoft has plans to update the Windows API for modern C++ usage with their win32metadata project.[13] Currently, there is C++/WinRT and "Windows Implementation Library" (WIL) for doing this in modern C++. Microsoft has also created bindings for other languages, including C# and Rust for calling the Win32 API.[14]
See also
[edit]References
[edit]- ↑ NI (21 February 2023). "Precompiled Headers". ni.com. NI (Emerson).
- 1 2 "Windows Data Types". learn.microsoft.com. 7 November 2024.
- ↑ "guiddef.h header". learn.microsoft.com. 23 January 2023.
- ↑ "winerror.h header". learn.microsoft.com. 23 January 2023.
- ↑ "wingdi.h header". learn.microsoft.com. 23 January 2023.
- ↑ "winnetwk.h header". learn.microsoft.com. 23 January 2023.
- ↑ "winnt.h header". learn.microsoft.com. 23 January 2023.
- ↑ "winreg.h header". learn.microsoft.com. 23 January 2023.
- ↑ "MAKEINTRESOURCEA macro (winuser.h)". learn.microsoft.com. 19 November 2024.
- ↑ "DialogBoxA macro (winuser.h)". learn.microsoft.com. 22 February 2024.
- ↑ "winuser.h header". learn.microsoft.com. 23 January 2023.
- ↑ "winver.h header". learn.microsoft.com. 23 January 2023.
- ↑ "Making Win32 APIs More Accessible to More Languages". blogs.windows.com. 21 January 2021.
- ↑ "win32metadata". Retrieved 4 September 2025.
