socket学习（一）

环境vs2008

1.把WinSock2.h头文件包含进来；

2.把Ws2_32.lib链接库加进来；

3.相关代码：

void DoSocket()
{
    WSADATA wsaData;
    WSAStartup(MAKEWORD(2, 0), &wsaData);
    SOCKET sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    SOCKADDR_IN sa;
    sa.sin_family = AF_INET;

    sa.sin_port = htons(IPPORT_SMTP);
    // 123.125.50.133 网易邮箱ip
    sa.sin_addr.S_un.S_addr = inet_addr("123.125.50.133");
    if (connect(sock, (SOCKADDR *)&sa, sizeof(sa)) == SOCKET_ERROR)
    {
        ShowError();
        return;
    }

    char buffer[256];
    ZeroMemory(buffer, sizeof(buffer) / sizeof(char));
    recv(sock, buffer, 256, 0);
    MessageBox(NULL, buffer, "", 0);

    TCHAR cQuit[] = "QUIT\n";
    send(sock, cQuit, lstrlen(cQuit), 0);
    ZeroMemory(buffer, sizeof(buffer) / sizeof(char));

    recv(sock, buffer, 256, 0);
    MessageBox(NULL, buffer, "", 0);

    closesocket(sock);
    WSACleanup();
}

void ShowError()
{
    TCHAR* lpMsgBuf;
    FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER|
        FORMAT_MESSAGE_FROM_SYSTEM,
        NULL, GetLastError(),
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
        (LPTSTR)&lpMsgBuf,
        0,
        NULL);
    MessageBox(NULL, lpMsgBuf, "", MB_ICONERROR);
}