C语言Socket网络通信基础一

一、客户端代码

#include 
#include 
#include
#include
#pragma comment(lib,"ws2_32.lib")
char receiveBuf[1024];
char sendBuf[1024];
int main()
{
    int err;
    WORD versionRequired;
    WSADATA wsaData;
    versionRequired=MAKEWORd(2,2);
    err=WSAStartup(versionRequired,&wsaData);

    if (!err)
    {
        printf("The socket of Client has opened!n");
    }
    else
    {
        printf("The socket of Client failed to open!n");
        return 0;
    }
    SOCKET clientSocket=socket(AF_INET,SOCK_STREAM,0);
    char ip_s[100];
    printf("Please input the IP of Server!n");
    scanf("%s",ip_s);
    SOCKADDR_IN clientsock_in;
    clientsock_in.sin_addr.S_un.S_addr=inet_addr(ip_s);
    clientsock_in.sin_family=AF_INET;
    clientsock_in.sin_port=htons(6000);


    connect(clientSocket,(SOCKADDR*)&clientsock_in,sizeof(SOCKADDR));

    char r_or_s;
    while(1)
    {
        printf("Input the operation char! Input ; to close the Client!n");
        fflush(stdin);
        scanf("%c",&r_or_s);
        printf("The client input %c!n",r_or_s);
        if(r_or_s=='r'||r_or_s=='R')
        {
            recv(clientSocket,receiveBuf,sizeof(char)*1024,0);
            printf("%sn",receiveBuf);
        }
        else if (r_or_s=='s'||r_or_s=='S')
        {
            printf("Input the information to Server!n");
            scanf("%s",sendBuf);
            send(clientSocket,sendBuf,sizeof(char)*1024,0);
        }
        else if(r_or_s==';')
        {
            printf("Close the cilent");
            break;
        }
    }
    closesocket(clientSocket);
    WSACleanup();
    return 0;
}

二、服务端代码

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


char sendBuf[1024];
char receiveBuf[1024];
char *account_file = "D:/code/C/socket/basin/file_transmission/account.txt";
int Login_account(SOCKET serConn)
{
    FILE *fp;
    int read_fp=0;
    char account_id[10],account_pwd[10];
    fp = fopen(account_file,"rb");
    if(fp==NULL)
    {
        printf("The file %s does not exit!",account_file);
        fclose(fp);
        return 0;
    }
    sprintf(sendBuf,"Please input the ID of the account!n");
    send(serConn,sendBuf,strlen(sendBuf)+1,0);
    recv(serConn,receiveBuf,sizeof(char)*1024,0);
    printf("The client want to login the account whose ID is %sn",receiveBuf);
    while(1)
    {
        read_fp=fscanf(fp,"%s %s",account_id,account_pwd);
        if(read_fp==-1)
        {
            sprintf(sendBuf,"Can't find the account!n");
            send(serConn,sendBuf,strlen(sendBuf)+1,0);
            fclose(fp);
            return 0;
        }
        if(strcmp(account_id,receiveBuf)==0)
        {
            sprintf(sendBuf,"Please input the password of the account!n");
            send(serConn,sendBuf,strlen(sendBuf)+1,0);
            fclose(fp);
            break;
        }
    }
    int pwd_time =1;
    while(pwd_time<4)
    {
        recv(serConn,receiveBuf,sizeof(char)*1024,0);
        if (strcmp(receiveBuf,account_pwd)==0)
        {
            sprintf(sendBuf,"Login the account successfully!n");
            send(serConn,sendBuf,strlen(sendBuf)+1,0);
            printf("One account has login,ID:%s PWD:%sn",account_id,account_pwd);
            return 1;
        }
    }
    sprintf(sendBuf,"Login the account unsuccessfully!n");
    send(serConn,sendBuf,strlen(sendBuf)+1,0);
    return 0;
}
void Register_account(SOCKET serConn)
{
    FILE *fp;
    int read_fp = 0;
    char account_id[10],account_pwd[10];
    fp = fopen(account_file,"rb");
    if(fp==NULL)
    {
        printf("The file %s does not exit!",account_file);
        fclose(fp);
        return 0;
    }
    sprintf(sendBuf,"Please input the ID of the account!n");
    send(serConn,sendBuf,strlen(sendBuf)+1,0);
    recv(serConn,receiveBuf,sizeof(char)*1024,0);
    printf("The client input the ID:%sn",receiveBuf);

    while(1)
    {
        read_fp=fscanf(fp,"%s %s",account_id,account_pwd);
        if(read_fp==-1)
        {
            sprintf(sendBuf,"Please input the password of the account!n");
            send(serConn,sendBuf,strlen(sendBuf)+1,0);
            fclose(fp);
            break;
        }
        if(strcmp(account_id,receiveBuf)==0)
        {
            sprintf(sendBuf,"The account has exited!Please change the ID!n");
            send(serConn,sendBuf,strlen(sendBuf)+1,0);
            fclose(fp);
            return;
        }
    }

    strcpy(account_id,receiveBuf);
    recv(serConn,receiveBuf,sizeof(char)*1024,0);
    printf("The Client input the password:%s",receiveBuf);
    strcpy(account_pwd,receiveBuf);
    fp = fopen(account_file,"a");
    fprintf(fp,"n%s %s",account_id,account_pwd);
    fclose(fp);
    sprintf(sendBuf,"One new account register successfully!n ID:%s   password:%s",account_id,account_pwd);
    send(serConn,sendBuf,strlen(sendBuf)+1,0);
    return ;
}
int main()
{
    WORD myVersionRequest;
    WSADATA wsaData;
    myVersionRequest=MAKEWORd(2,2);
    int err;
    err=WSAStartup(myVersionRequest,&wsaData);
    if (!err)
    {
        printf("The socket of Server has opened!n");
    }
    else
    {
        printf("The socket of Server failed to open!n");
        return 0;
    }
    SOCKET serSocket=socket(AF_INET,SOCK_STREAM,0);
    SOCKADDR_IN addr;
    addr.sin_family=AF_INET;
    addr.sin_addr.S_un.S_addr=htonl(INADDR_ANY);
    addr.sin_port=htons(6000);

    bind(serSocket,(SOCKADDR*)&addr,sizeof(SOCKADDR));
    listen(serSocket,5);

    SOCKADDR_IN clientsocket;
    int len=sizeof(SOCKADDR);
    SOCKET serConn=accept(serSocket,(SOCKADDR*)&clientsocket,&len);
    char L_or_R;
    char exit_C;
    int login_judge = 0;
    while(1)
    {
        sprintf(sendBuf,"Please first to login or register!n L/l(login)  R/r(Register)n");
        send(serConn,sendBuf,strlen(sendBuf)+1,0);
        recv(serConn,receiveBuf,sizeof(char)*1024,0);
        printf("The client input the %s!n",receiveBuf);

        printf("The Client %s choose to %c!n",inet_ntoa(clientsocket.sin_addr),receiveBuf[0]);
        L_or_R = receiveBuf[0];
        if(L_or_R=='L'||L_or_R == 'l')
            login_judge=Login_account(serConn);
        else if (L_or_R=='R'||L_or_R == 'r')
        {
            Register_account(serConn);
            login_judge=Login_account(serConn);
        }
        else
        {
            sprintf(sendBuf,"Stop to login account!n");
            send(serConn,sendBuf,strlen(sendBuf)+1,0);
            printf("Stop to server? Y/y N/n n");
            scanf("%s",&exit_C);
            if(exit_C=='Y'||exit_C=='y')
                break;
        }

        if(login_judge==0)
            continue;

    }
    printf("Stop the server successfully!n");
    sprintf(sendBuf,"The server have stopped");
    send(serConn,sendBuf,strlen(sendBuf)+1,0);
    closesocket(serConn);
    WSACleanup();
    return 0;
}

三、实现功能和使用方法 1、注册用户：注意修改服务端的账号保存文件路径 2、登录用户：会提示没有注册的用户 3、服务端：不需要多余输入操作 4、客户端：输入S/s向服务端发射信息，R/r接收服务端信息,输入;关闭客户端，如果客户端窗口没有服务端的提示，则选择接收信息，否则则选择发射信息。 四、可能存在的问题 1、客户端输入的IP地址为服务端的IP地址，通常为在CMD窗口输入ipconfig后的WLAN的IP地址。 2、客户端在服务端没有发射信息时选择接收信息，会导致卡死，需要重新操作。 五、参考文章 １、socket技术详解（看清socket编程）