编写一个基于Windows Socket的c语言程序。该程序允许多个用户同时在互联网上进行沟通。已经有了“server.cpp”和“client.cpp”，请补全这个程序的代码，并保证写入log到txt中。

以下是一个基于Windows Socket的c语言程序的代码示例，包括了“server.cpp”和“client.cpp”的补全部分，同时将聊天记录写入log.txt中。

server.cpp:

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

#pragma comment(lib,"ws2_32.lib") //Winsock Library

#define BUF_SIZE 200
#define MAX_CLNT 256

void error_handling(char *message);

int main(int argc, char *argv[])
{
    WSADATA wsaData;
    SOCKET hServSock, hClntSock;
    SOCKADDR_IN servAddr, clntAddr;

    int szClntAddr;
    char message[BUF_SIZE];
    int i, strLen;

    if(argc!=2) {
        printf("Usage : %s <port>\n", argv[0]);
        exit(1);
    }

    if(WSAStartup(MAKEWORD(2,2), &wsaData)!=0)
        error_handling("WSAStartup() error!");

    hServSock=socket(PF_INET, SOCK_STREAM, 0);
    if(hServSock == INVALID_SOCKET)
        error_handling("socket() error");

    memset(&servAddr, 0, sizeof(servAddr));
    servAddr.sin_family=AF_INET;
    servAddr.sin_addr.s_addr=htonl(INADDR_ANY);
    servAddr.sin_port=htons(atoi(argv[1]));

    if(bind(hServSock, (SOCKADDR*)&servAddr, sizeof(servAddr))==SOCKET_ERROR)
        error_handling("bind() error");

    if(listen(hServSock, 5)==SOCKET_ERROR)
        error_handling("listen() error");

    while(1)
    {
        szClntAddr=sizeof(clntAddr);
        hClntSock=accept(hServSock, (SOCKADDR*)&clntAddr, &szClntAddr);
        if(hClntSock==INVALID_SOCKET)
            continue;

        while((strLen=recv(hClntSock, message, BUF_SIZE, 0))!=0)
        {
            fwrite(message, 1, strLen, stdout); //将收到的消息打印到控制台
            fwrite(message, 1, strLen, logfile); //将收到的消息写入log文件
            send(hClntSock, message, strLen, 0); //将收到的消息原封不动地发送回去
        }

        closesocket(hClntSock);
    }

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

void error_handling(char *message)
{
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}

client.cpp:

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

#pragma comment(lib,"ws2_32.lib") //Winsock Library

#define BUF_SIZE 200

void error_handling(char *message);

int main(int argc, char *argv[])
{
    WSADATA wsaData;
    SOCKET hSocket;
    SOCKADDR_IN servAddr;
    char message[BUF_SIZE];
    int strLen;

    if(argc!=3) {
        printf("Usage : %s <IP> <port>\n", argv[0]);
        exit(1);
    }

    if(WSAStartup(MAKEWORD(2,2), &wsaData)!=0)
        error_handling("WSAStartup() error!");

    hSocket=socket(PF_INET, SOCK_STREAM, 0);
    if(hSocket == INVALID_SOCKET)
        error_handling("socket() error");

    memset(&servAddr, 0, sizeof(servAddr));
    servAddr.sin_family=AF_INET;
    servAddr.sin_addr.s_addr=inet_addr(argv[1]);
    servAddr.sin_port=htons(atoi(argv[2]));

    if(connect(hSocket, (SOCKADDR*)&servAddr, sizeof(servAddr))==SOCKET_ERROR)
        error_handling("connect() error!");

    while(1)
    {
        fputs("Input message(Q to quit): ", stdout);
        fgets(message, BUF_SIZE, stdin);

        if(!strcmp(message,"q\n") || !strcmp(message,"Q\n"))
            break;

        send(hSocket, message, strlen(message), 0);
        strLen=recv(hSocket, message, BUF_SIZE-1, 0);
        message[strLen]=0;
        fwrite(message, 1, strLen, stdout); //将收到的消息打印到控制台
        fwrite(message, 1, strLen, logfile); //将收到的消息写入log文件
    }

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

void error_handling(char *message)
{
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}