C语言WinSock学习笔记第2/2页

以下是C语言WinSock学习笔记第2/2页的完整攻略：

概述

WinSock（Windows套接字）是一组用于网络编程的API，最初由Microsoft开发并在Windows95上引入。WinSock API使得开发人员可以使用C语言编写网络应用程序，如web浏览器和FTP客户端等。本文将介绍如何使用WinSock API进行网络编程，构建客户端和服务器程序。

客户端

在WinSock中，客户端程序的基本工作流程如下：

• 初始化WinSock库
• 创建套接字
• 连接到服务器
• 从服务器接收数据（如果需要）
• 关闭套接字和WinSock库

下面是一个简单的示例，它演示了如何使用WinSock API编写一个s客户端程序：

#include <stdio.h>
#include <stdlib.h>
#include <winsock2.h>

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

int main() {
    WSADATA wsaData;
    SOCKET ConnectSocket;
    struct sockaddr_in serv_addr;
    char receiveBuffer[256];
    int iResult;
    int receiveSize = 256;

    iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
    if (iResult) {
        printf("WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

    ConnectSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (ConnectSocket == INVALID_SOCKET) {
        printf("socket failed with error: %ld\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(80);
    serv_addr.sin_addr.s_addr = inet_addr("74.125.24.106");

    iResult = connect(ConnectSocket, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
    if (iResult == SOCKET_ERROR) {
        printf("connect failed with error: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }

    iResult = recv(ConnectSocket, receiveBuffer, receiveSize, 0);
    if (iResult > 0) {
        printf("Received: %s\n", receiveBuffer);
    } else if (iResult == 0) {
        printf("Connection closed\n");
    } else {
        printf("recv failed with error: %d\n", WSAGetLastError());
    }

    closesocket(ConnectSocket);
    WSACleanup();

    return 0;
}

上述代码将建立与Google首页的TCP连接，并将收到的数据打印到控制台上。

服务器端

在WinSock中，服务器程序的基本工作流程如下：

• 初始化WinSock库
• 创建套接字，并将其与一个IP地址和端口号绑定
• 在套接字上侦听传入的连接请求
• 接受连接请求
• 从客户端接收数据（如果需要）
• 处理客户端请求
• 关闭连接和套接字，并清除WinSock库

下面是一个简单的示例，它演示了如何使用WinSock API编写一个UDP服务器程序：

#include <stdio.h>
#include <stdlib.h>
#include <winsock2.h>

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

int main() {
    WSADATA wsaData;
    SOCKET ListenSocket;
    struct sockaddr_in serv_addr, cli_addr;
    char receiveBuffer[256];
    int iResult;
    int receiveSize = 256;
    int cli_len;

    iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
    if(iResult) {
        printf("WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

    ListenSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
    if(ListenSocket == INVALID_SOCKET) {
        printf("socket failed with error: %ld\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    memset((char *)&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(9000);
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);

    iResult = bind(ListenSocket, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
    if(iResult == SOCKET_ERROR) {
        printf("bind failed with error: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
        return 1;
    }

    while(1) {
        printf("Waiting for datagrams...\n");
        memset((char *)&cli_addr, 0, sizeof(cli_addr));
        iResult = recvfrom(ListenSocket, receiveBuffer, receiveSize, 0, (struct sockaddr *)&cli_addr, &cli_len);
        if(iResult == SOCKET_ERROR) {
            printf("recvfrom failed with error: %d\n", WSAGetLastError());
            closesocket(ListenSocket);
            WSACleanup();
            return 1;
        } else {
            receiveBuffer[iResult] = '\0';
            printf("Received datagram from client: %s\n", receiveBuffer);

            iResult = sendto(ListenSocket, "Hello from server!", 19, 0, (struct sockaddr *)&cli_addr, sizeof(cli_addr));
            if(iResult == SOCKET_ERROR) {
                printf("sendto failed with error: %d\n", WSAGetLastError());
                closesocket(ListenSocket);
                WSACleanup();
                return 1;
            } else {
                printf("Sent %d bytes to client\n", iResult);
            }
        }
    }

    closesocket(ListenSocket);
    WSACleanup();

    return 0;
}

上述代码将侦听UDP数据报，将收到的数据报打印到控制台上，并向客户端发送一个字符串"Hello from server!"。

希望以上内容对你有所帮助。