pipetest.c

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//
//pipe方式进程间通信演示程序 from 0472223
//
#include<unistd.h>
#include<sys/types.h>
#include<errno.h>
main()
{
      int pipe_fd[2];
      pid_t pid;
      char r_buf[100];
      char w_buf[4];
      char* p_wbuf;
      int r_num;
      int cmd;
      memset(r_buf,0,sizeof(r_buf));
      memset(w_buf,0,sizeof(r_buf));
      p_wbuf=w_buf;
      if(pipe(pipe_fd)<0)
      {
                         printf("pipe create error.\n");
                         return -1;
                         }
      if((pid=fork())==0) //若返回为0,说明是子进程 
      {
                         printf("\n");
                         close(pipe_fd[1]);//关闭写操作 
                         sleep(3);
                         r_num=read(pipe_fd[0],r_buf,100);
                         printf("read num is %d the data read from the pepe is %d\n",r_num,atoi(r_buf));
                         close(pipe_fd[0]);
                         exit(0);
                         }
      else if(pid>0)//是父进程 
      {
           close(pipe_fd[0]);
           strcpy(w_buf,"111");//写入111 
           if(write(pipe_fd[1],w_buf,4)!=-1)
                                            printf("parent write over\n");
           close(pipe_fd[1]);
           printf("parent close fd[1] over.\n");
           sleep(10);//进入阻塞态 
      }
}