IPC  有命管道

      创建一个有名管道  /tmp/stduent.data

      A 和 B 是 相对独立的两支程序，现在 A  传送  10 个Student 到  B

      B 将Student 读取出来，显示在界面上

   

      然后 B  传送  10 个 Teacher 到  A  ，A 显示 teacher 在界面上

 

A.cpp

#include "public.h"

#define FIFO_NAME "/temp/Linux/my_fifo"

#define BUFFER_SIZE PIPE_BUF

#define TEN_MEG (1024*1024*10)

typedef struct students

{

 int no;

 char username[100];

}*StuNode,SNode;

 

int main()

{

 int pipe_fd;

 int ret;

 int open_mode=O_WRONLY;

 int bytes=0;

 char buffer[BUFFER_SIZE+1];

 SNode stus[10];

 for (int i=0;i<10;i++)

 {

  stus[i].no=i+1;

  strcpy(stus[i].username,"student");

 }

 if (access(FIFO_NAME,F_OK)==-1)

 {

  ret=mkfifo(FIFO_NAME,0777);

  if (ret!=0)

  {

   fprintf(stderr,"Could not create fifo %s\n",FIFO_NAME);

   exit(EXIT_FAILURE);

  }

 }

 printf("Process %d opening FIFO O_WRONLY\n",getpid());

 pipe_fd=open(FIFO_NAME,open_mode);

 printf("Process %d result %d\n",getpid(),pipe_fd);

 if (pipe_fd!=-1)

 {

  while (bytes<10)

  {

   ret=write(pipe_fd,&stus[bytes],sizeof(SNode));

   if (ret==-1)

   {

    fprintf(stderr,"write error on pipe\n");

    exit(EXIT_FAILURE);

   }

   bytes++;

  }

  close(pipe_fd);

 }

 else

 {

  exit(EXIT_FAILURE);

 }

 printf("Process %d finish \n",getpid());

 exit(EXIT_FAILURE);

 return 0;

}

 

 B.cpp

#include "public.h"

#define FIFO_NAME "/temp/Linux/my_fifo"

#define BUFFER_SZIE PIPE_BUF

typedef struct students

{

 int no;

 char username[100];

}*StuNode,SNode;

 

int main()

{

 int pipe_fd;

 int ret;

 int open_mode=O_RDONLY;

 char buffer[BUFFER_SZIE+1];

 int bytes=0;

 SNode stus[10];

 memset(buffer,'\0',sizeof(buffer));

 printf("Process %d opening FIFO O_RDONLY\n",getpid());

 pipe_fd=open(FIFO_NAME,open_mode);

 if (pipe_fd!=-1)

 {

  do

  {

   ret=read(pipe_fd,&stus[bytes],sizeof(SNode));

   printf("no = %d username = %s \n",stus[bytes].no,stus[bytes].username);

   bytes++;

  } while (ret>0);

  close(pipe_fd);

 }

 else

  exit(EXIT_FAILURE);

 printf("Process %d finished,%d bytes read\n",getpid(),bytes);

 exit(EXIT_FAILURE);

 return 0;

}