#include是在.h文件还是.cpp文件中为什么为什么重要？

Question

I have a cpp file contains this include:

#include "twitServer.h"

and in twitServer.h I have:

#ifndef twitServer_twitServer_h
#define twitServer_twitServer_h
#include <string>
#include <map>
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <list>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <cstring>
#include <netdb.h>
#include <errno.h>
#include <sstream>
#include <algorithm>
#include <ctime>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include "twitUser.h"

using namespace std;

void startServer(string port);

#endif

But the Xcode says for this line:

if ((rv = getaddrinfo(NULL, port, &hints, &ai)) != 0) {
    fprintf(stderr, "selectserver: %s\n", gai_strerror(rv));
    exit(1);
}

that the getaddrinfo is not defined... why that?

if the includes are in the cpp file it works fine how comes

Answer 1

不确定如何解决问题，但按照惯例，您绝对不应将其包含在头文件中，因为有一天可能会编写代码，需要头文件，但不是所有包含的内容。

Answer 2

Try including Ws2tcpip.h and see if that solves the problem. This is what MSDN has to say about it (see the requirements section)

http://msdn.microsoft.com/en-us/library/windows/desktop/ms738520%28v=vs.85%29.aspx

Also, let me say that this seems like an awful lot of header files included and some should not be matched unless you really know what you are doing. There are quite a bit of C++ headers (iostream (which is included twice by the way), cstdio, cstdlib, algorithm, list, string, ctime...) mixed with C headers (stdio.h, stdlib.h string.h). Maybe it's time for some late spring cleaning in there :)