c-选择循环如何使其变得更好

Question

我选择了N管道，我的问题是：捕获后，一个"pipe-选择不起作用。可能我没有删除i描述符。以下是我的问题：
1） 我真的必须在C中制作类似vector的动态数组并插入和删除i
2） 如何使我的代码更好？如何使用select解决问题？

我的代码：

while(1)
        {
                sel = select(val+1,&set,NULL,NULL,&timeout);
                if(sel < 0)
                        perror("Blad funkcji select");
                else if(sel == 0)
                        printf("Brak komunikatow n");
                else{
                        for(i = 0; i < val; i++)
                        {
                                if(FD_ISSET(fd[i][0],&set))
                                {
                                   while(read(fd[i][0],&buf,rozmiar) > 0)
                                   write(1,&buf,rozmiar);

                                } // check if exist and write to stdout

                } // end SELECT
                for(i = 0, j =0; i< val; i++)
                {
                        FD_SET(fd[i][0], &set);
                }
                timeout.tv_sec = 4;
                timeout.tv_usec = 0;
        }

Answer 1

返回值顶部

   On success, select() and pselect() return the number of file
   descriptors contained in the three returned descriptor sets (that is,
   the total number of bits that are set in readfds, writefds,
   exceptfds) which may be zero if the timeout expires before anything
   interesting happens.  On error, -1 is returned, and errno is set to
   indicate the error; the file descriptor sets are unmodified, and
   timeout becomes undefined.

 if(sel ==-1)
                perror("Blad funkcji select");