急！socket编程错误!__buffer_include_sockfd_printf_sizeof_

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急！socket编程错误!

来源: 互联网发布时间：2016-03-17

本文导语: 刚编了一个服务器和客户端的程序功能是客户端向服务器端发送消息，服务器端接受并显示可是当第一次向服务器端发送消息时，服务器端能正常显示但是接下来再向服务器端发送时，服务器端没有响应！ server.c如...

刚编了一个服务器和客户端的程序
功能是客户端向服务器端发送消息，服务器端接受并显示
可是当第一次向服务器端发送消息时，服务器端能正常显示
但是接下来再向服务器端发送时，服务器端没有响应！
server.c如下：
#include
#include
#include
#include
#include
#include
#include
#include

#define      MYPORT 7777
#define BACKLOG 10

int main(int argc, char **argv)
{
        char buffer[1024];
        int sockfd,new_fd      ;
        int sin_size;
        struct sockaddr_in my_addr ;
        struct sockaddr_in their_addr ;
        if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
        {
        printf("create sockn");
        return -1;
        }
        else
        {
      my_addr.sin_family= AF_INET ;
      my_addr.sin_port= htons(MYPORT);
      my_addr.sin_addr.s_addr=inet_addr("192.168.1.5") ;
      bzero(&(my_addr.sin_zero),8);
      if (bind (sockfd, (struct sockaddr *)&my_addr,sizeof(struct sockaddr))==-1)
        {

               printf("bind errorn");
                return -1 ;
        }
      listen(sockfd, BACKLOG);
                sin_size = sizeof(struct sockaddr_in);
                new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size);
                if(new_fd == -1)
                {
                        printf("accept errorn");
                }
                char *msg = "Hello client! ";
                int len, bytes_sent;
                len = strlen(msg);
                bytes_sent = send(new_fd, msg, len, 0);
                printf("okn");
                int nbytes;
                //bzero(buffer,sizeof(buffer));
                while(1)
                {
                if((nbytes=read(new_fd,buffer,1024))==-1)
                {
                        perror("read errorn");
                        exit(1);
                }
                buffer[nbytes]='';
                printf("I have received:%sn",buffer);
                /*bzero(buffer,sizeof(buffer));
                scanf("%s",buffer);
                int len, bytes_sent;
                bytes_sent = write(sockfd, buffer,strlen(buffer));
                printf("okn");
                */
                //close(new_fd);
                }
                //close(sockfd);
        }
}

client.c 如下：

#include
#include
#include
#include
#include
#include
#include
#include
#include
#define MYPORT 7777
#define BACKLOG 10
int main(int argc, char **argv)
{
        int sockfd;

        char buffer[1024];
        struct sockaddr_in server_addr;
        struct hostent *host;
        int portnumber,nbytes;
        if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
        {
        printf("socket errorn");
        return -1 ;
        }
        bzero(&server_addr,sizeof(server_addr));
        server_addr.sin_family=AF_INET;
        server_addr.sin_port=htons(MYPORT);
        server_addr.sin_addr.s_addr= inet_addr("192.168.1.5") ;
        int nsock;
        nsock=connect(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr));
        if(nsock==-1)
        {
        perror("connect errorn");
        return -1;
        }
        while(1)
        {
/*      if((nbytes=read(sockfd,buffer,1024))==-1)
        {
        printf("read errorn");
        return -1 ;
        }
        buffer[nbytes]='';
        printf("I have received:%sn",buffer);
        */
        bzero(buffer,sizeof(buffer));
        scanf("%s",buffer);
        int len, bytes_sent;
        bytes_sent = write(sockfd, buffer,strlen(buffer));
        printf("okn");
        }
        close(sockfd);
}

server端的接收：while((nbytes=recv(new_fd,buffer,sizeof(buffer), 0)) == -1)

由于你的socket是阻塞方式的，那么每次recv一定要收全sizeof(buffer)个字节才会返回，否则一直阻塞，
再看看buffer的声明：char buffer[1024]; 那么sizeof(buffer)就是1024，
于是每次recv操作一定要收全1024个字节才会返回。

client端的发送：if((bytes_sent = send(sockfd, buffer,strlen(buffer), 0))