c++ linux套接字服务器反复调用客户端

Question

所以我对如何让服务器多次与我的客户端来回发送数据感到困惑。目前服务器将向客户端发送数据，然后客户端将发回答案，但我不知道如何在不一次又一次启动客户端服务器的情况下多次执行此操作。

基本上我想知道如何在不创建新客户端的情况下让服务器和客户端重复通信。

这是我的服务器代码。我正在创建一个随机数，然后使用客户端来确定它的因素

#include <iostream>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <time.h> 
#include <cmath>

using namespace std;

int *findPrimes(int primeArray[])
{
    int i, j, n = 100000, flag;
    //int primeArray[65];
    int count = 0;

    for(i = 2; i <= n; i++)
    {
        flag = 1;
        for(j =2;j<=i/2;j++)
        {
            if(i%j==0)
            {
                flag = 0;
                break;
            }
        }
        if(flag==1)
        {
            primeArray[count] = i;
            count++;
        }
    }
    return primeArray;
}

int calcNumber()
{
    srand(time(NULL));

    int base = rand()%9 + 2;
    int numCalc[5];
    bool isntBase = false;
    int count = 0;
    int testNum;

    do{
        testNum = rand() % 100000;
        int number = testNum;
        cout << base << ", " << number << endl;
        count = 0;
        isntBase = false;

        for(int i = 0; i < 5; i++)
        {
            numCalc[i] = 0;
        }

        while (number > 0)
        {
            int digit = number%10;
            number /= 10;
            numCalc[count] = digit;
            count++;
            if(digit >= base)
            {
                isntBase = true;
            }
        }
    }while(isntBase == true);

    cout << testNum << "(" << base <<")";
    int decConvert = 0;
    int baseMult = 1;
    for(int i = 0; i < 5; i++)
    {
        //cout << numCalc[i] << endl;
        decConvert += numCalc[i]*(pow(base, i));
        //baseMult = baseMult * 7;
        //cout << decConvert << endl;
    }
    cout << " = " << decConvert << "(10) = ";
    return decConvert;
}


int main(int argc, char *argv[])
{
    int listenfd = 0, connfd = 0;
    struct sockaddr_in serv_addr; 

    char sendBuff[1025];
    time_t ticks; 

    int n = 3;
    int numOfPrime= 0;
    bool isPrime = false;
    bool noMorePlease = false;
    int y[9592];
    int *prime = findPrimes(y);

    int number = calcNumber();

    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    memset(&serv_addr, '0', sizeof(serv_addr));
    memset(sendBuff, '0', sizeof(sendBuff)); 

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(5575); 

    bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)); 

    listen(listenfd, 2); 

    int prcount = 0;

    while(noMorePlease == false){
        //Thread

        int client_socket;
        client_socket = accept(listenfd, NULL, NULL);

        int primeNum = prime[prcount];
        send(client_socket, &number, sizeof(number),0);
        send(client_socket, &primeNum,sizeof(primeNum), 0);

        int recvNum = 0;
        //char recvVal[256];   
        //recv(listenfd, &number, sizeof(number), 0);
        recv(client_socket, &recvNum, sizeof(recvNum), 0);

        //cout << endl << recvNum;

        if(recvNum >0)
        {
            cout << prime[prcount] << "^" << recvNum <<"*";
        }
        while(recvNum > 0)
        {
            number = number/prime[prcount];
            recvNum--;
        }
        prcount++;
        if(number == 1)
        {
            cout << endl;
            numOfPrime = 0;
            noMorePlease = true;
        }
        if(prcount > 9592)
        {
            numOfPrime++;
            cout << " a prime number!" << endl;
            numOfPrime++;
            if(numOfPrime == n)
            {
                noMorePlease = true;
                cout << "There were " << n << " primes in a row" << endl;
                close(listenfd);
                return 0;
            }
        }
        //close(client_socket);
    }

    close(listenfd);
    return 0;
}

这是我的客户端代码

#include <iostream>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h> 

using namespace std;

int main(int argc, char *argv[])
{
    int sockfd = 0, n = 0;
    char recvBuff[1024];
    struct sockaddr_in serv_addr; 


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

    memset(recvBuff, '0',sizeof(recvBuff));
    if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        printf("\n Error : Could not create socket \n");
        return 1;
    } 

    memset(&serv_addr, '0', sizeof(serv_addr)); 

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(5575); 

    if(inet_pton(AF_INET, argv[1], &serv_addr.sin_addr)<=0)
    {
        printf("\n inet_pton error occured\n");
        return 1;
    } 

    if( connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
    {
       printf("\n Error : Connect Failed \n");
       return 1;
    } 
    int number = 0;
    int primeNum;
    char recvVal[256];   
    recv(sockfd, &number, sizeof(number), 0);
    recv(sockfd, &primeNum, sizeof(primeNum), 0);

    int divCount = 0;

    cout << number << ", " << primeNum << endl;
    while(number % primeNum == 0)
    {
        cout << number << ",  ";
        number =  number/primeNum;
        divCount++;
    }

    cout << endl << divCount;
    send(sockfd, &divCount,sizeof(divCount), 0);

    /*
    while ( (n = read(sockfd, recvBuff, sizeof(recvBuff)-1)) > 0)
    {
        recvBuff[n] = 0;
        if(fputs(recvBuff, stdout) == EOF)
        {
            printf("\n Error : Fputs error\n");
        }
    } 

    if(n < 0)
    {
        printf("\n Read error \n");
    } 
*/
    close(sockfd);
    return 0;
}

Answer 1

在您的客户端代码中，在行之后:

if( connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)

您应该在一个循环中执行recv 和send，以便连接保持打开状态。完成后，退出循环并关闭套接字。此方法的示例使用同步套接字，可在此处找到:https://vcansimplify.wordpress.com/2013/03/14/c-socket-tutorial-echo-server/