C#套接字和windowsAPI套接字

C#服务器端

第一步：用指定的端口号和服务器的ip建立一个EndPoint对像；
第二步：建立一个Socket对像；
第三步：用socket对像的Bind()方法绑定EndPoint；
第四步：用socket对像的Listen()方法开始监听；
第五步：接受到客户端的连接，用socket对像的Accept()方法创建新的socket对像用于和请求的客户端进行通信;
第六步：通信结束后一定记得关闭socket

            int port = 8889;
            string host = "127.0.0.1";

            ///创建终结点（EndPoint）
            IPAddress ip = IPAddress.Parse(host);//把ip地址字符串转换为IPAddress类型的实例
            IPEndPoint ipe = new IPEndPoint(ip, port);//用指定的端口和ip初始化IPEndPoint类的新实例

            ///创建socket并开始监听
            /// 
            Socket s = new Socket(SocketType.Stream, ProtocolType.Tcp);//创建一个socket对像，如果用udp协议，则要用SocketType.Dgram类型的套接字
            s.Bind(ipe);//绑定EndPoint对像（2000端口和ip地址）
            s.Listen(0);//开始监听
            Console.WriteLine("等待客户端连接服务器为{0}:{1}",host,port);

            ///接受到client连接，为此连接建立新的socket，并接受信息
            Socket temp = s.Accept();//为新建连接创建新的socket
            Console.WriteLine("建立连接");
            string recvStr = "";
            byte[] recvBytes = new byte[1024];
            int bytes= temp.Receive(recvBytes, recvBytes.Length, 0);//从客户端接受信息
            recvStr += Encoding.ASCII.GetString(recvBytes, 0, bytes);

            ///给client端返回信息
            Console.WriteLine("server get message:{0}", recvStr);//把客户端传来的信息显示出来
            string sendStr = "ok!Client send message successful!";
            byte[] bs = Encoding.ASCII.GetBytes(sendStr);
            temp.Send(bs, bs.Length, 0);//返回信息给客户端
            temp.Close();
            s.Close();
            Console.ReadLine();

C#客户端

第一步：用指定的端口号和服务器的ip建立一个EndPoint对像；
第二步：建立一个Socket对像；
第三步：用socket对像的Connect()方法以上面建立的EndPoint对像做为参数，向服务器发出连接请求；
第四步：如果连接成功，就用socket对像的Send()方法向服务器发送信息；
第五步：用socket对像的Receive()方法接受服务器发来的信息 ;
第六步：通信结束后一定记得关闭socket；

　　　　　　　　　　int port = 8889;
                string host = "127.0.0.1";
                ///创建终结点EndPoint
                IPAddress ip = IPAddress.Parse(host);
                IPEndPoint ipe = new IPEndPoint(ip, port);//把ip和端口转化为IPEndpoint实例

                ///创建socket并连接到服务器
                
                Socket c = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);//创建Socket
                Console.WriteLine("Conneting…");
                c.Connect(ipe);//连接到服务器

                ///向服务器发送信息
                string sendStr = "hello!This is a socket test";
                byte[] bs = Encoding.ASCII.GetBytes(sendStr);//把字符串编码为字节
                Console.WriteLine("Send Message");
                c.Send(bs, bs.Length, 0);//发送信息

                ///接受从服务器返回的信息 
                byte[] recvBytes = new byte[1024];
                int bytes;
                bytes = c.Receive(recvBytes, recvBytes.Length, 0);//从服务器端接受返回信息
               string recvStr = Encoding.ASCII.GetString(recvBytes, 0, bytes);
                Console.WriteLine("client get message:{0}", recvStr);//显示服务器返回信息
                                                                     ///一定记着用完socket后要关闭
                c.Close();

 windows API服务器端

//Server.cpp
#include <iostream>
#include <winsock2.h>

using namespace std;

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

#define PORT 8889
#define IP_ADDRESS "127.0.0.1"


DWORD WINAPI ClientThread(LPVOID lpParameter)
{
    SOCKET CientSocket = (SOCKET)lpParameter;
    int Ret = 0;
    char RecvBuffer[MAX_PATH];

    while (true)
    {
        memset(RecvBuffer, 0x00, sizeof(RecvBuffer));
        Ret = recv(CientSocket, RecvBuffer, MAX_PATH, 0);
        if (Ret == 0 || Ret == SOCKET_ERROR)
        {
            cout << "客户端退出!" << endl;
            break;
        }
        cout << "接收到客户信息为:" << RecvBuffer << endl;
    }

    return 0;
}

int main(int argc, char* argv[])
{
    WSADATA  Ws;
    SOCKET ServerSocket, ClientSocket;
    struct sockaddr_in LocalAddr, ClientAddr;
    int Ret = 0;
    int AddrLen = 0;
    HANDLE hThread = NULL;

    //Init Windows Socket
    if (WSAStartup(MAKEWORD(2, 2), &Ws) != 0)
    {
        cout << "Init Windows Socket Failed::" << GetLastError() << endl;
        return -1;
    }

    //Create Socket
    ServerSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (ServerSocket == INVALID_SOCKET)
    {
        cout << "Create Socket Failed::" << GetLastError() << endl;
        return -1;
    }

    LocalAddr.sin_family = AF_INET;
    LocalAddr.sin_addr.s_addr = inet_addr(IP_ADDRESS);
    LocalAddr.sin_port = htons(PORT);
    memset(LocalAddr.sin_zero, 0x00, 8);

    //Bind Socket
    Ret = bind(ServerSocket, (struct sockaddr*)&LocalAddr, sizeof(LocalAddr));
    if (Ret != 0)
    {
        cout << "Bind Socket Failed::" << GetLastError() << endl;
        return -1;
    }
    //listen
    Ret = listen(ServerSocket, 10);
    if (Ret != 0)
    {
        cout << "listen Socket Failed::" << GetLastError() << endl;
        return -1;
    }

    cout << "服务端已经启动" << endl;

    while (true)
    {
        AddrLen = sizeof(ClientAddr);
        ClientSocket = accept(ServerSocket, (struct sockaddr*)&ClientAddr, &AddrLen);
        if (ClientSocket == INVALID_SOCKET)
        {
            cout << "Accept Failed::" << GetLastError() << endl;
            break;
        }

        cout << "客户端连接::" << inet_ntoa(ClientAddr.sin_addr) << ":" << ClientAddr.sin_port << endl;

        hThread = CreateThread(NULL, 0, ClientThread, (LPVOID)ClientSocket, 0, NULL);
        if (hThread == NULL)
        {
            cout << "Create Thread Failed!" << endl;
            break;
        }

        CloseHandle(hThread);
    }

    closesocket(ServerSocket);
    closesocket(ClientSocket);
    WSACleanup();

    return 0;
}

windows API客户端

// Client.cpp
#include <iostream>
#include <winsock2.h>
using namespace std;

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

#define PORT 8889
#define IP_ADDRESS "127.0.0.1"

int main(int argc, char * argv[])
{
    WSADATA Ws;
    SOCKET ClientSocket;
    struct sockaddr_in ServerAddr;
    int Ret = 0;
    int AddrLen = 0;
    HANDLE hThread = NULL;
    char SendBuffer[MAX_PATH];

    //Init Windows Socket
    if (WSAStartup(MAKEWORD(2, 2), &Ws) != 0)
    {
        cout << "Init Windows Socket Failed::" << GetLastError() << endl;
        return -1;
    }
    //Create Socket
    ClientSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (ClientSocket == INVALID_SOCKET)
    {
        cout << "Create Socket Failed::" << GetLastError() << endl;
        return -1;
    }

    ServerAddr.sin_family = AF_INET;
    ServerAddr.sin_addr.s_addr = inet_addr(IP_ADDRESS);
    ServerAddr.sin_port = htons(PORT);
    memset(ServerAddr.sin_zero, 0x00, 8);

    Ret = connect(ClientSocket, (struct sockaddr*)&ServerAddr, sizeof(ServerAddr));
    if (Ret == SOCKET_ERROR)
    {
        cout << "Connect Error::" << GetLastError() << endl;
        return -1;
    }
    else
    {
        cout << "连接成功!" << endl;
    }

    while (true)
    {
        cin.getline(SendBuffer, sizeof(SendBuffer));
        Ret = send(ClientSocket, SendBuffer, (int)strlen(SendBuffer), 0);
        if (Ret == SOCKET_ERROR)
        {
            cout << "Send Info Error::" << GetLastError() << endl;
            break;
        }
    }

    closesocket(ClientSocket);
    WSACleanup();

    return 0;
}
网络字节序与主机字节序转换，有如下4个函数：
　　htons(),htonl(),ntohs(),ntohl()
h表示host字节序，n表示net字节序，s表示short，l表示long。
htons是将整型变量从主机字节顺序转变成网络字节顺序， 就是整数在地址空间存储方式变为：高位字节存放在内存的低地址处。
网络字节顺序是TCP/IP中规定好的一种数据表示格式，它与具体的CPU类型、操作系统等无关，从而可以保证数据在不同主机之间传输时能够被正确解释，网络字节顺序采用big-endian排序方式。
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原文地址：https://www.cnblogs.com/weiyinfu/p/5349271.html