Windows套接字API绑定函数编译问题

Question

I am trying to bind a tcp socket on windows and when expecting an integer back from the function I get a compile error. I am not a c++ programmer and usually do not work on Windows so I am having trouble tracking this issue down. One thing I did notice was that if I did not include the winsock header file all of the other functions I use dealing with sockets such as send, recv, accept and connect all raise compile errors but one was not raised for the bind function. This leads me to believe that I am some how pulling in a different bind function then I am expecting.

The list of included header files for the entire application

#include <fstream>
#include <string>
#include <ctime> 
#include <mutex>
#include <stdio.h>
#include <strsafe.h>
#include <map>
#include <iterator>
#include <process.h>
#include <queue>
#include <iostream>
#include <winsock.h>

The included library's are

#pragma comment(lib, "Ws2_32.lib")
#pragma comment(lib, "User32.lib")

And the class that is trying to use the bind function is

//implement an interface for udp and tcp socket classes to implement
class Socket 
{
public:
    virtual void sendm(const char *buf) = 0;
    virtual int recvm(char *buf) = 0;

    struct hostent  *phe;       /* pointer to host information entry    */
    struct servent  *pse;       /* pointer to service information entry */
    struct protoent *ppe;       /* pointer to protocol information entry  */
    struct sockaddr_in sin;     /* an Internet endpoint address     */
    int type, status;       /* socket descriptor and socket type */
    SOCKET s;                   /* socket */
};

class TCPSocket : public Socket {
public:
    TCPSocket(const char *host, const char *service, bool master_socket){
        initialize_socket(host, service, master_socket);
    }
    ~TCPSocket(void);


    SOCKET initialize_socket(const char *host, const char *service, bool master_socket) {
        cout << "host: " << host << endl;
        cout << "service: " << service << endl;
        char* transport = "tcp";
        int qlen = 10;
        int portbase = 0;
        memset(&sin, 0, sizeof(sin));
        sin.sin_family = AF_INET;
        if (pse = getservbyname(service, transport) ) {
            sin.sin_port = htons(ntohs((u_short)pse->s_port) + portbase);
        }
        else if ((sin.sin_port = htons((u_short)atoi(service))) == 0)
        {
            cout << "can't get " << service << " service" << endl;
            exit(1);
        }

        /* Map protocol name to protocol number */
        if ( (ppe = getprotobyname(transport)) == 0)  {
            cout << "Can't get \"" << transport << "\" protocol entry "<< endl;
            exit(1);
        }

        /* Map host name to IP address, allowing for dotted decimal */
        if (master_socket) {
            sin.sin_addr.s_addr = htonl( INADDR_ANY ); 
        } 
        else {
            if ( phe = gethostbyname(host) ) {
                memcpy(&sin.sin_addr, phe->h_addr, phe->h_length);
            }
            else if ( (sin.sin_addr.s_addr = inet_addr(host)) == INADDR_NONE) {
                cout << "Can't get \"" << host << "\" IP address "<< endl;
                exit(1);
            }
        }


        type = SOCK_STREAM;

        s = socket(AF_INET, type, ppe->p_proto);

        if (s == INVALID_SOCKET) {
            cout << "Socket Error: " << GetLastError() << endl;
            exit(1);
        }

        if (master_socket) {    
            status = bind(s, (sockaddr *)&sin, sizeof(sin));
            /* if (status != 0) { */
            /*   cout << "Bind Error: " << service << " port: " << GetLastError(); */
            /* } */
            status = listen(s, qlen);
            if (status != 0) {
                cout << "can't listen on " << service << " port: " << GetLastError();
                exit(1);
            }
        } else {    
            int status = connect(s, (struct sockaddr*)&sin, sizeof(sin));
            if ( status != 0 ) {
                cout << "could not connect" << endl;
                exit(1);
            }
        }
        return s;       
    }

    SOCKET acceptSocket() {
        return accept(s, (struct sockaddr*)&sin, (int*)sizeof(sin)); 
    }

    void sendm(const char *buf) {
        send(s, buf, strlen(buf), 0);
    }

    int recvm(char *buf) {
        return recv(s, buf, BUFFER_SIZE, 0);
    }
};

The documentation on bind on msdn says this function returns an int.

The compile error I get when attempting to compile is

error C2440: '=' : cannot convert from 'std::_Bind<_Forced,_Ret,_Fun,_V0_t,_V1_t,_V2_t,_V3_t,_V4_t,_V5_t,<unnamed-symbol>>' to 'int'
with
[
    _Forced=false,
    _Ret=void,
    _Fun=SOCKET &,
    _V0_t=sockaddr *,
    _V1_t=unsigned int,
    _V2_t=std::_Nil,
    _V3_t=std::_Nil,
    _V4_t=std::_Nil,
    _V5_t=std::_Nil,
    <unnamed-symbol>=std::_Nil
]
No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called

I am working with Windows 8 running on a VM in VirtualBox. I am using Visual Studios 2012 command developer command line to compile my code. Any suggestions as to why bind is not working as expected would be very much appreciated.

Answer 1

This leads me to believe that I am some how pulling in a different bind function then I am expecting.

Yes, you are pulling in std::bind . If you look inside <mutex> it has this line #include <functional> which includes std::bind . You probably have a using namespace std; somewhere which makes all the names from the std namespace visible.

Also, the bind you want is in Winsock2.h , and I didn't see an #include for it.

Please read Why is 'using namespace std;' considered a bad practice in C++? . I would recommend removing any using directives (which is probably the cause of this issue) and fully qualify everything.

Answer 2

when using <mutex> and have "using namespace std"

use ::bind() instead of bind()