win32 socket之select

之前光看理论是不行滴，一定要实践，实践啊，不然永远都是门外汉！！

嗯嗯，把找到的一段源码贴上先,稍微修改了一下：

#include <winsock.h>
#include <stdio.h>

#include <string>

#define PORT       5010
#define MSGSIZE    1024
int BytesSum = 0;

#pragma comment(lib, "ws2_32.lib")

DWORD WINAPI WorkerThread(LPVOID lpParameter);

void InitWinSocket() 
{
    WSADATA     wsaData;
    WSAStartup(0x0202, &wsaData);
}

#define ListenQ 10

int main()
{
    InitWinSocket();

    int opt = TRUE;
    int master_socket , addrlen , new_socket , client_socket[30] , max_clients = 30 , activity, i , valread , sd;
    int max_sd;
    struct sockaddr_in address;

    char buffer[1025];  //data buffer of 1K

    //set of socket descriptors
    fd_set readfds;

    //a message
    char *message = "ECHO Daemon v1.0 
";

    //initialise all client_socket[] to 0 so not checked
    for (i = 0; i < max_clients; i++) 
    {
        client_socket[i] = 0;
    }

    //create a master socket
    if( (master_socket = socket(AF_INET , SOCK_STREAM , 0)) == 0) 
    {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    //set master socket to allow multiple connections , this is just a good habit, it will work without this
    if( setsockopt(master_socket, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, sizeof(opt)) < 0 )
    {
        perror("setsockopt");
        exit(EXIT_FAILURE);
    }

    //type of socket created
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons( PORT );

    //bind the socket to localhost port 8888
    if (bind(master_socket, (struct sockaddr *)&address, sizeof(address))<0) 
    {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }
    printf("Listener on port %d 
", PORT);

    //try to specify maximum of 3 pending connections for the master socket
    if (listen(master_socket, 3) < 0)
    {
        perror("listen");
        exit(EXIT_FAILURE);
    }

    //accept the incoming connection
    addrlen = sizeof(address);
    puts("Waiting for connections ...");

    while(TRUE) 
    {
        //clear the socket set
        FD_ZERO(&readfds);

        //add master socket to set
        FD_SET(master_socket, &readfds);
        max_sd = master_socket;

        //add child sockets to set
        for ( i = 0 ; i < max_clients ; i++) 
        {
            //socket descriptor
            sd = client_socket[i];

            //if valid socket descriptor then add to read list
            if(sd > 0)
                FD_SET( sd , &readfds);

            //highest file descriptor number, need it for the select function
            if(sd > max_sd)
                max_sd = sd;
        }

        //wait for an activity on one of the sockets , timeout is NULL , so wait indefinitely
        activity = select( max_sd + 1 , &readfds , NULL , NULL , NULL);

        if (activity < 0) 
        {
            printf("select error");
        }

        //If something happened on the master socket , then its an incoming connection
        if (FD_ISSET(master_socket, &readfds)) 
        {
            if ((new_socket = accept(master_socket, (struct sockaddr *)&address,&addrlen))<0)
            {
                perror("accept");
                exit(EXIT_FAILURE);
            }

            //inform user of socket number - used in send and receive commands
            printf("New connection , socket fd is %d , ip is : %s , port : %d 
" , new_socket , inet_ntoa(address.sin_addr) , ntohs(address.sin_port));

            //send new connection greeting message
            if( send(new_socket, message, strlen(message), 0) != strlen(message) ) 
            {
                perror("send");
            }

            puts("Welcome message sent successfully");

            //add new socket to array of sockets
            for (i = 0; i < max_clients; i++) 
            {
                //if position is empty
                if( client_socket[i] == 0 )
                {
                    client_socket[i] = new_socket;
                    printf("Adding to list of sockets as %d
" , i);

                    break;
                }
            }
        }

        //else its some IO operation on some other socket :)
        for (i = 0; i < max_clients; i++) 
        {
            sd = client_socket[i];

            if (FD_ISSET( sd , &readfds)) 
            {
                //Check if it was for closing , and also read the incoming message
                if ((valread = recv( sd , buffer, 1024,0)) == 0)
                {
                    //Somebody disconnected , get his details and print
                    getpeername(sd , (struct sockaddr*)&address , &addrlen);
                    printf("Host disconnected , ip %s , port %d 
" , inet_ntoa(address.sin_addr) , ntohs(address.sin_port));

                    //Close the socket and mark as 0 in list for reuse
                    closesocket( sd );
                    client_socket[i] = 0;
                }

                //Echo back the message that came in
                else
                {
                    //set the string terminating NULL byte on the end of the data read
                    buffer[valread] = '';
                    send(sd , buffer , strlen(buffer) , 0 );
                }
            }
        }
    }

    return 0;
}

ok，回家慢慢学习！