今天寫(xiě)一個(gè)小程序出現(xiàn)了這種問(wèn)題：
>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(91) : warning C4005: “AF_IPX”: 宏重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(460) : 參見(jiàn)“AF_IPX”的前一個(gè)定義
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(127) : warning C4005: “AF_MAX”: 宏重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(479) : 參見(jiàn)“AF_MAX”的前一個(gè)定義
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(163) : warning C4005: “SO_DONTLINGER”: 宏重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(402) : 參見(jiàn)“SO_DONTLINGER”的前一個(gè)定義
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(206) : error C2011: “sockaddr”: “struct”類型重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(485) : 參見(jiàn)“sockaddr”的聲明
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(384) : error C2143: 語(yǔ)法錯(cuò)誤 : 缺少“}”(在“常量”的前面)
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(384) : error C2143: 語(yǔ)法錯(cuò)誤 : 缺少“;”(在“常量”的前面)
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(384) : error C2059: 語(yǔ)法錯(cuò)誤 : “常量”
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(437) : error C2143: 語(yǔ)法錯(cuò)誤 : 缺少“;”(在“}”的前面)
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(437) : error C4430: 缺少類型說(shuō)明符 - 假定為 int。注意: C++ 不支持默認(rèn) int
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(437) : error C4430: 缺少類型說(shuō)明符 - 假定為 int。注意: C++ 不支持默認(rèn) int
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(518) : warning C4005: “IN_CLASSA”: 宏重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(287) : 參見(jiàn)“IN_CLASSA”的前一個(gè)定義
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(524) : warning C4005: “IN_CLASSB”: 宏重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(293) : 參見(jiàn)“IN_CLASSB”的前一個(gè)定義
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(530) : warning C4005: “IN_CLASSC”: 宏重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(299) : 參見(jiàn)“IN_CLASSC”的前一個(gè)定義
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(541) : warning C4005: “INADDR_ANY”: 宏重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(304) : 參見(jiàn)“INADDR_ANY”的前一個(gè)定義
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(543) : warning C4005: “INADDR_BROADCAST”: 宏重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(306) : 參見(jiàn)“INADDR_BROADCAST”的前一個(gè)定義
1>c:\program files\microsoft sdks\windows\v6.0a\include\ws2def.h(577) : error C2011: “sockaddr_in”: “struct”類型重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(312) : 參見(jiàn)“sockaddr_in”的聲明
1>c:\program files\microsoft sdks\windows\v6.0a\include\winsock2.h(132) : error C2011: “fd_set”: “struct”類型重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(68) : 參見(jiàn)“fd_set”的聲明
1>c:\program files\microsoft sdks\windows\v6.0a\include\winsock2.h(167) : warning C4005: “FD_SET”: 宏重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(102) : 參見(jiàn)“FD_SET”的前一個(gè)定義
1>c:\program files\microsoft sdks\windows\v6.0a\include\winsock2.h(176) : error C2011: “timeval”: “struct”類型重定義
1>        c:\program files\microsoft sdks\windows\v6.0a\include\winsock.h(111) : 參見(jiàn)“timeval”的聲明


好久沒(méi)寫(xiě)TCP的程序了，都忘記是怎么回事了，隱約記得解決方法很簡(jiǎn)單。搜索了一下，記錄下來(lái)：

引用鏈接：http://www.cnblogs.com/tonyyang132/archive/2009/10/14/1583110.html

初看到如此一堆的錯(cuò)誤委實(shí)不爽，但是只要將二者的包含順序調(diào)換一下問(wèn)題就會(huì)解決，原因參見(jiàn)下面那個(gè)鏈接。另外，上述問(wèn)題不僅影響直接包含二者的文件，還影響間接包含的情形。比如，a.h包含了windows.h，b.h包含了winsock2.h，如果在c.h當(dāng)中要引用a.h和b.h，那么正確的順序應(yīng)當(dāng)是b.h先于a.h。當(dāng)然，實(shí)踐當(dāng)中有時(shí)很難找到究竟是哪兩個(gè)文件順序不對(duì)了，終極的解決辦法是，在當(dāng)前工程（就是編譯不過(guò)的這個(gè)工程）所有include語(yǔ)句最前面加上#include <winsock2.h>和#include<windows.h>，世界清靜了。


關(guān)于WINSOCK.H與winsock2.h中的重定義解決辦法分析

問(wèn)題描述：在 VC 6.0中使用socket相關(guān)的函數(shù)時(shí)沒(méi)有什么問(wèn)題，可是到了.net下就有以下類似的錯(cuò)誤，

[C++ Error] winsock2.h(109): E2238 Multiple declaration for 'fd_set'
[C++ Error] winsock.h(54): E2344 Earlier declaration of 'fd_set'
[C++ Error] winsock2.h(112): E2146 Need an identifier to declare
[C++ Warning] winsock2.h(144): W8017 Redefinition of 'FD_SET' is not identical
[C++ Error] winsock2.h(153): E2238 Multiple declaration for 'timeval'
[C++ Error] winsock.h(97): E2344 Earlier declaration of 'timeval'
[C++ Error] winsock2.h(209): E2238 Multiple declaration for 'hostent'
[C++ Error] winsock.h(153): E2344 Earlier declaration of 'hostent'
[C++ Error] winsock2.h(222): E2238 Multiple declaration for 'netent'
[C++ Error] winsock.h(166): E2344 Earlier declaration of 'netent'
[C++ Error] winsock2.h(229): E2238 Multiple declaration for 'servent'
[C++ Error] winsock.h(173): E2344 Earlier declaration of 'servent'
[C++ Error] winsock2.h(241): E2238 Multiple declaration for 'protoent'
[C++ Error] winsock.h(185): E2344 Earlier declaration of 'protoent'
[C++ Error] winsock2.h(327): E2238 Multiple declaration for 'in_addr'
[C++ Error] winsock.h(269): E2344 Earlier declaration of 'in_addr'
[C++ Error] winsock2.h(385): E2238 Multiple declaration for 'sockaddr_in'
[C++ Error] winsock.h(319): E2344 Earlier declaration of 'sockaddr_in'
[C++ Error] winsock2.h(395): E2238 Multiple declaration for 'WSAData'
[C++ Error] winsock.h(329): E2344 Earlier declaration of 'WSAData'
[C++ Error] winsock2.h(411): E2146 Need an identifier to declare
[C++ Warning] winsock2.h(455): W8017 Redefinition of 'SO_DONTLINGER' is not identical
[C++ Warning] winsock2.h(512): W8017 Redefinition of 'AF_IPX' is not identical
[C++ Warning] winsock2.h(540): W8017 Redefinition of 'AF_MAX' is not identical
[C++ Error] winsock2.h(546): E2238 Multiple declaration for 'sockaddr'
[C++ Error] winsock.h(492): E2344 Earlier declaration of 'sockaddr'
[C++ Error] winsock2.h(586): E2238 Multiple declaration for 'sockproto'
[C++ Error] winsock.h(501): E2344 Earlier declaration of 'sockproto'
[C++ Error] winsock2.h(625): E2238 Multiple declaration for 'linger'
[C++ Error] winsock2.h(625): E2228 Too many error or warning messages

Solution：

This problem arises because windows.h (at least, that version of it) includes not winsock2.h but winsock.h; sadly when Microsoft wrote winsock2.h they chose neither to change windows.h to include winsock2.h, which replaces winsock.h, nor to include windows.h from winsock2.h and then add the definitions for the new Winsock 2 API methods & structures (this might seem reasonable since Winsock 2 does, strictly speaking, replace Winsock 1, but since the API must be fully backwards-compatible the distinction is somewhat meaningless and there's no real benefit to making winsock2.h standalone).

The fix is thankfully simple: always "#include <winsock2.h>" before windows.h.

However, you must remember that if windows.h has been included by (for example) a higher-level header file that is subsequently including your header file, it's too late - so you must make sure that the higher-level header files respect this convention also.

It is however rarely necessary to modify the header files of libraries or other code modules you are using just because you include their header files, and their header files include windows.h - you can just include winsock2.h before you include the library's header files.

在包含jrtplib有時(shí)候我也遇到這個(gè)問(wèn)題，解決方法與之相同。一句話，在#include<windows.h>之前 #include <winsock2.h> 問(wèn)題就可以解決。

問(wèn)題描述]
   在包含了<windows.h>以及<winsock2.h>的工程中,編譯有時(shí)會(huì)出現(xiàn)如
下錯(cuò)誤:
     error C2011: 'fd_set' : 'struct' type redefinition
     error C2011: 'timeval' : 'struct' type redefinition
                     ....
     error C2375: 'accept' : redefinition; different linkage
[原因分析]
   主要原因是因?yàn)?lt;windows.h>中包含了<winsock.h>頭文件,由于其版
本的不同，導(dǎo)致出現(xiàn)上述的錯(cuò)誤。<windows.h>中相關(guān)代碼如下:
               #ifndef WIN32_LEAN_AND_MEAN
               #include <cderr.h>
               #include <dde.h>
               #include <ddeml.h>
               ........
                #ifndef _MAC
               #include <winperf.h>
               #include <winsock.h>
               #endif
                .......
               #include <commdlg.h>
               #endif
               #endif
[解決方案]
    由以上代碼可以看出如果在沒(méi)有定義WIN32_LEAN_AND_MEAN宏的大前
提下windows.h有可能包含winsock.h 頭文件，因此我們得出一個(gè)很簡(jiǎn)單
的解決方法就是在包含<windows.h>之前定義WIN32_LEAN_AND_MEAN宏,如
下所示:
#define WIN32_LEAN_AND_MEAN
#include <windows.h>