SOCKET编程：为什么recv不阻塞

服务器端：

 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <fstream>
 #include <sstream>
 #include <iostream>
 #include <vector>
 #include <error.h>
 using namespace std;
 
 int main()
 {
     double bs_x[] = {,-,,,-};
     double bs_y[] = {,,,-,-};
     //vector<vector<double> > tdoa;
     double tdoa[][];
 
     ifstream infile("otdoa.txt");
     if( !infile)
     {
         cout << "can't open otdoa.txt" << endl;
         return -;
     }
     int i = ;
     int j = ;
     while(infile)
     {
         string line;
         double a;
         //vector<double> ta;
         /*infile >> line;
         istringstream stream(line);
         int j = 0;
         while(stream >> a)
         {
             tdoa[i][j] = a;
             j++;
         }*/
         if( j == )
         {
             i++;
             j = ;
         }
         infile >> tdoa[i][j];
         j++;
         if(infile.peek() == '\n')
             break;
     }
     infile.close();
 
     int listenfd,confd;
     struct sockaddr_in servaddr;
 
     listenfd = socket(AF_INET,SOCK_STREAM,);
     if(listenfd < )
     {
         cout << "can't open socket" << endl;
         return -;
     }
 
     bzero(&servaddr,sizeof(servaddr));
     servaddr.sin_family = AF_INET;
     servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
     servaddr.sin_port = htons();
 
     if( bind(listenfd,(struct sockaddr*)&servaddr,sizeof(servaddr)) < )
     {
         //cout << "bind error" << endl;
         perror("bind error");
         return -;
     }
 
     if( listen(listenfd,) <  )
     {
         cout << "listen error" << endl;
         return -;
     }
 
     i = ;
 
     //confd = accept(listenfd,(struct sockaddr*)NULL,NULL);
     while()
     {
         confd = accept(listenfd,(struct sockaddr*)NULL,NULL);
         if( confd < )
         {
             cout << "accept error" << endl;
             return -;
         }
         pid_t pid;
         pid = fork();
         if( pid == )
         {
             close(listenfd);
             cout << "child" << endl;
         send(confd,bs_x,sizeof(bs_x),);
         send(confd,bs_y,sizeof(bs_y),);
         send(confd,tdoa[i],sizeof(tdoa[i]),);
         //close(confd);
         break;
         }
         cout << "parent" << endl;
         close(confd);
 
      i++;
      sleep();
     }
     cout << "child exit" << endl;
     close(confd);
     return ;
 }

客户端：

 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <fstream>
 #include <sstream>
 #include <iostream>
 using namespace std;
 
 int main()
 {
     struct data
     {
         double bs_x[];
         double bs_y[];
         double tdoa[];
     }data_t;
     struct data revdata;
     char buf[];
     int sockfd;
     struct sockaddr_in addr;
 
     sockfd = socket(AF_INET,SOCK_STREAM,);
 
     bzero(&addr,sizeof(addr));
     addr.sin_family = AF_INET;
     addr.sin_addr.s_addr = inet_addr("127.0.0.1");
     addr.sin_port = htons();
 
     if( connect(sockfd,(struct sockaddr*)&addr,sizeof(addr)) < )
     {
         cout << "connect error" << endl;
         return -;
     }
 
     struct sockaddr_in testaddr;
     bzero(&testaddr,sizeof(testaddr));
     getsockname(sockfd,(struct sockaddr*)&testaddr,NULL);
     char bbb[];
     inet_ntop(AF_INET,&testaddr.sin_addr,bbb,sizeof(testaddr));
     cout << bbb << endl;
     cout << ntohs(testaddr.sin_port) << endl;
     while()                                            //死循环
     {
     //menset(&buf,sizeof(buf));
     if( recv(sockfd,buf,sizeof(revdata),MSG_WAITALL) < )  //当服务器端断开连接时，recv失效
     {
         cout << "recieve msg erro" << endl;
         return -;
     }
 
     bzero(&revdata,);
     memcpy(&revdata,buf,sizeof(revdata));
 
     for(int i = ; i < ; i++)                //但是这里一直在死循环中输出
     {
         printf("[%d]\t",i+);
         cout << revdata.bs_x[i] <<" "
             << revdata.bs_y[i] << " "
             << revdata.tdoa[i] << endl;
     }
     }
     close(sockfd);
     return ;
 
 }

因为recv在客户端的死循环中，当服务端断开连接时，recv失效