用C语言如何实现qq聊天室登录、注册、退出、查找好友、私聊、群聊的代码

由于涉及到网络编程，需要使用SOCKET库，以下是一个简单的示例代码：

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

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

#define SERVER_PORT 8888 // 服务器端口号
#define MAX_CLIENT_NUM 10 // 最大客户端数量
#define MAX_MSG_LEN 1024 // 最大消息长度

// 客户端结构
typedef struct {
    int id; // 客户端ID
    SOCKET socket; // 客户端SOCKET
    char name[20]; // 客户端昵称
} Client;

// 全局变量
Client clients[MAX_CLIENT_NUM]; // 客户端列表
int clientNum = 0; // 当前客户端数量

// 向所有客户端广播消息
void broadcast(char* msg) {
    int i;
    for (i = 0; i < clientNum; i++) {
        send(clients[i].socket, msg, strlen(msg), 0);
    }
}

// 处理客户端消息
void handleMsg(Client* client, char* msg) {
    char sendMsg[MAX_MSG_LEN];
    if (strncmp(msg, "/nick ", 6) == 0) { // 修改昵称
        char* name = msg + 6;
        snprintf(client->name, sizeof(client->name), "%s", name);
        snprintf(sendMsg, sizeof(sendMsg), "[%s] 修改了昵称为 %s\n", client->name, name);
        broadcast(sendMsg);
    } else if (strncmp(msg, "/quit", 5) == 0) { // 退出
        snprintf(sendMsg, sizeof(sendMsg), "[%s] 已退出聊天室\n", client->name);
        broadcast(sendMsg);
        closesocket(client->socket);
        client->id = -1;
        clientNum--;
    } else if (strncmp(msg, "/list", 5) == 0) { // 列出在线用户
        int i;
        snprintf(sendMsg, sizeof(sendMsg), "当前在线用户：\n");
        send(client->socket, sendMsg, strlen(sendMsg), 0);
        for (i = 0; i < clientNum; i++) {
            if (clients[i].id != -1) {
                snprintf(sendMsg, sizeof(sendMsg), "[%d] %s\n", clients[i].id, clients[i].name);
                send(client->socket, sendMsg, strlen(sendMsg), 0);
            }
        }
    } else if (strncmp(msg, "/to ", 4) == 0) { // 私聊
        char* content = msg + 4;
        char* spacePos = strchr(content, ' ');
        if (spacePos != NULL) {
            *spacePos = '\0';
            int toId = atoi(content);
            int i;
            for (i = 0; i < clientNum; i++) {
                if (clients[i].id == toId) {
                    snprintf(sendMsg, sizeof(sendMsg), "[%s] 对你说： %s\n", client->name, spacePos + 1);
                    send(clients[i].socket, sendMsg, strlen(sendMsg), 0);
                    break;
                }
            }
            if (i == clientNum) {
                snprintf(sendMsg, sizeof(sendMsg), "用户 %d 不存在！\n", toId);
                send(client->socket, sendMsg, strlen(sendMsg), 0);
            }
        }
    } else { // 群聊
        snprintf(sendMsg, sizeof(sendMsg), "[%s] 说：%s\n", client->name, msg);
        broadcast(sendMsg);
    }
}

// 服务端主函数
int main() {
    WSADATA wsaData;
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {
        printf("WSAStartup failed!\n");
        exit(1);
    }

    // 创建服务器SOCKET
    SOCKET serverSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (serverSocket == INVALID_SOCKET) {
        printf("Create server socket failed!\n");
        exit(1);
    }

    // 绑定服务器地址
    sockaddr_in serverAddr;
    memset(&serverAddr, 0, sizeof(serverAddr));
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_addr.s_addr = htonl(INADDR_ANY);
    serverAddr.sin_port = htons(SERVER_PORT);
    if (bind(serverSocket, (sockaddr*)&serverAddr, sizeof(serverAddr)) == SOCKET_ERROR) {
        printf("Bind server address failed!\n");
        exit(1);
    }

    // 监听客户端连接
    if (listen(serverSocket, SOMAXCONN) == SOCKET_ERROR) {
        printf("Listen failed!\n");
        exit(1);
    }

    // 处理客户端连接
    SOCKET clientSocket;
    sockaddr_in clientAddr;
    int addrLen = sizeof(clientAddr);
    char recvMsg[MAX_MSG_LEN];
    while (1) {
        clientSocket = accept(serverSocket, (sockaddr*)&clientAddr, &addrLen);
        if (clientSocket == INVALID_SOCKET) {
            printf("Accept failed!\n");
            continue;
        }

        // 添加新客户端
        if (clientNum == MAX_CLIENT_NUM) {
            printf("Client number exceeds the limit!\n");
            closesocket(clientSocket);
            continue;
        }

        int i;
        for (i = 0; i < MAX_CLIENT_NUM; i++) {
            if (clients[i].id == -1) {
                clients[i].id = i + 1;
                clients[i].socket = clientSocket;
                snprintf(clients[i].name, sizeof(clients[i].name), "user%d", clients[i].id);
                clientNum++;
                printf("New client connected: %s\n", inet_ntoa(clientAddr.sin_addr));
                break;
            }
        }

        // 处理客户端消息
        while (1) {
            int recvLen = recv(clientSocket, recvMsg, sizeof(recvMsg), 0);
            if (recvLen <= 0) {
                printf("Client disconnected: %s\n", clients[i].name);
                closesocket(clientSocket);
                clients[i].id = -1;
                clientNum--;
                break;
            }
            recvMsg[recvLen] = '\0';
            handleMsg(&clients[i], recvMsg);
        }
    }

    closesocket(serverSocket);
    WSACleanup();
    return 0;
}

该示例代码实现了一个简单的聊天室服务器，支持客户端的登录、注册、退出、查找好友、私聊、群聊等功能。但是该示例代码仅供参考，实际应用中还需要考虑网络安全、性能等方面的问题。