if ((sd = accept(socket_d,(struct sockaddr *)&client_addr,&alen)) < 0)
{
    perror("accept Failed\n");
    exit(1);
}

我如何知道客户端已退出的服务器端.

我的整个程序实际上做了以下..

>接受来自客户端的连接
>启动从该特定客户端读取消息的新线程,然后将此消息广播到所有连接的客户端.

如果你想看到整个代码…在这整个代码.我也遇到一个问题,每当我用Ctrl C杀死一个客户端,我的服务器突然终止..如果有人可以建议什么问题,这将是很好的

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

/*CONSTANTS*/
#define DEFAULT_PORT 10000 
#define LISTEN_QUEUE_LIMIT 6
#define TOTAL_CLIENTS 10
#define CHAR_BUFFER 256

/*GLOBAL VARIABLE*/
int current_client = 0;
int connected_clients[TOTAL_CLIENTS];
extern int errno;

void *client_handler(void * socket_d);

int main(int argc,char *argv[])
{
    struct sockaddr_in server_addr;/* structure to hold server's address*/
    int    socket_d;             /* listening socket descriptor       */
    int    port;           /* protocol port number              */
    int    option_value;   /* needed for setsockopt             */
    pthread_t tid[TOTAL_CLIENTS];
    port = (argc > 1)?atoi(argv[1]):DEFAULT_PORT;

    /* Socket Server address structure */
    memset((char *)&server_addr,sizeof(server_addr)); 
    server_addr.sin_family = AF_INET;               /* set family to Internet */
    server_addr.sin_addr.s_addr = INADDR_ANY;       /* set the local IP address */
    server_addr.sin_port = htons((u_short)port);    /* Set port */

    /* Create socket */
    if ( (socket_d = socket(PF_INET,SOCK_STREAM,0)) < 0) {
        fprintf(stderr,"socket creation Failed\n");
        exit(1);
    }

    /* Make listening socket's port reusable */
    if (setsockopt(socket_d,SOL_SOCKET,SO_REUSEADDR,(char *)&option_value,sizeof(option_value)) < 0) {
        fprintf(stderr,"setsockopt failure\n");
        exit(1);
    }

    /* Bind a local address to the socket */
    if (bind(socket_d,(struct sockaddr *)&server_addr,sizeof(server_addr)) < 0) {
        fprintf(stderr,"bind Failed\n");
        exit(1);
    }

    /* Specify size of request queue */
    if (listen(socket_d,LISTEN_QUEUE_LIMIT) < 0) {
        fprintf(stderr,"listen Failed\n");
        exit(1);
    }

    memset(connected_clients,sizeof(int)*TOTAL_CLIENTS);

    for (;;)
    {
        struct sockaddr_in client_addr;    /* structure to hold client's address*/
        int    alen = sizeof(client_addr); /* length of address                 */
        int    sd;                /* connected socket descriptor */

        if ((sd = accept(socket_d,&alen)) < 0)
        {
            perror("accept Failed\n");
            exit(1);
        }
        else printf("\n I got a connection from (%s,%d)\n",inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));

        if (pthread_create(&tid[current_client],NULL,(void *)client_handler,(void *)sd) != 0)
        {
            perror("pthread_create error");
            continue;
        }
        connected_clients[current_client]=sd;
        current_client++; /*Incrementing Client number*/
    }

    return 0;
}

void *client_handler(void *connected_socket)
{
    int sd;
    sd = (int)connected_socket;
    for ( ; ; ) 
    {
        ssize_t n;
        char buffer[CHAR_BUFFER];
        for ( ; ; )
        {
            if (n = read(sd,buffer,sizeof(char)*CHAR_BUFFER) == -1)
            {
                perror("Error reading from client");
                pthread_exit(1);
            }
            int i=0;
            for (i=0;i<current_client;i++)
            {
                if (write(connected_clients[i],sizeof(char)*CHAR_BUFFER) == -1)
                    perror("Error sending messages to a client while multicasting");
            }
        }
    }
}

我的客户端是(Maye在回答我的问题时无关紧要)

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 
#include <string.h>
#include <stdlib.h>

void error(char *msg)
{
    perror(msg);
    exit(0);
}

void *listen_for_message(void * fd)
{
    int sockfd = (int)fd;
    int n;
    char buffer[256];
    bzero(buffer,256);
    printf("YOUR MESSAGE: ");
    fflush(stdout);
    while (1)
    {
        n = read(sockfd,256);
        if (n < 0) 
            error("ERROR reading from socket");
        if (n == 0) pthread_exit(1);
        printf("\nMESSAGE BROADCAST: %sYOUR MESSAGE: ",buffer);
        fflush(stdout);
    }
}

int main(int argc,char *argv[])
{
    int sockfd,portno,n;
    struct sockaddr_in serv_addr;
    struct hostent *server;
    pthread_t read_message;
    char buffer[256];
    if (argc < 3) {
        fprintf(stderr,"usage %s hostname port\n",argv[0]);
        exit(0);
    }
    portno = atoi(argv[2]);
    sockfd = socket(AF_INET,0);
    if (sockfd < 0) 
        error("ERROR opening socket");
    server = gethostbyname(argv[1]);
    if (server == NULL) {
        fprintf(stderr,"ERROR,no such host\n");
        exit(0);
    }
    bzero((char *) &serv_addr,sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr,(char *)&serv_addr.sin_addr.s_addr,server->h_length);
    serv_addr.sin_port = htons(portno);
    if (connect(sockfd,&serv_addr,sizeof(serv_addr)) < 0) 
        error("ERROR connecting");
    bzero(buffer,256);
    if (pthread_create(&read_message,(void *)listen_for_message,(void *)sockfd) !=0 )
    {
        perror("error creating thread");
    }
    while (1)
    {
        fgets(buffer,255,stdin);
        n = write(sockfd,256);
        if (n < 0) 
            error("ERROR writing to socket");
        bzero(buffer,256);
    }
    return 0;
}