Problems caused by the inclusion sequence of windows. h and winsock2.h

Environment:

Windows, C ++

Error description:

Socket and thread used in the project, corresponding to include header files # include <winsock2.h> and # include <windows. h>

However, many errors are encountered during compilation, almost all of which are errors such as "type/link redefinition" and "unable to find identifiers", and almost all occur in winsock2.h and ws2def. h;

For example:

Error c2011: "sockaddr_in": "struct" type redefinition
Ws2def. h

Error c2375: "accept": redefinition; different links winsock2.h

Error c3861: "socket": unable to find the identifier server. cpp

Error cause:

Header files are often included in network development.

# Include <winsock2.h>

# Include <windows. h>

If the order is incorrect (Windows. H is prior to winsock2.h), many inexplicable errors may occur.

The reason is: Windows. h contains Winsock. h header file, while a lot of content in winsock2.h will be related to Winsock. the content in H is the same, resulting in type redefinition (winsock2.h is Winsock. later versions of H)

Solution:

If the macro win32_lean_and_mean is not specified, windows. h contains Winsock. h.

Therefore, the solution is as follows:

Define the win32_lean_and_mean macro before including <windows. h>, as shown in
As shown below:
# Define win32_lean_and_mean
# Include <windows. h>

Supplement:

Windows. h contains the following content:

# Ifndef win32_lean_and_mean
# Include <cderr. h>
# Include <DDE. h>
# Include <ddeml. h>
# Include <DLGS. h>
# Ifndef _ Mac
# Include <lzexpand. h>
# Include <mmsystem. h>
# Include <nb30.h>
# Include <rpc. h>
# Endif
# Include <shellapi. h>
# Ifndef _ Mac
# Include <winperf. h>

# If (_ win32_winnt> = 0x0400)
# Include <winsock2.h>
# Include <mswsock. h>
# Else
# Include <Winsock. h>
# Endif/* _ win32_winnt> = 0x0400 */

# Endif
# Ifndef nocrypt
# Include <wincrypt. h>
# Endif

# Ifndef nogdi
# Include <commdlg. h>
# Ifndef _ Mac
# Include <winspool. h>
# Ifdef inc_ole1
# Include <Ole. h>
# Else
# Include <ole2.h>
# Endif /*! Inc_ole1 */
# Endif /*! Mac */
# Endif /*! Nogdi */
# Endif/* win32_lean_and_mean */