#include <unistd.h>
#include <sys/types.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main()
{
	int pipe_fd[2];
	pid_t pid;
	char buf_r[100];
	char* p_wbuf;
	int r_num;
	
	memset(buf_r,0,sizeof(buf_r));
	
	/*創建管道*/
	if(pipe(pipe_fd)<0)
	{
		printf("pipe create error\n");
		return -1;
	}
	
	/*創建子進程*/
	if((pid=fork())==0)  //子進程執行序列
	{
		printf("\n");
		close(pipe_fd[1]);//子進程先關閉了管道的寫端
		sleep(2); /*讓父進程先運行，這樣父進程先寫子進程才有內容讀*/
		if((r_num=read(pipe_fd[0],buf_r,100))>0)
		{
			printf("%d numbers read from the pipe is %s\n",r_num,buf_r);
		}	
		close(pipe_fd[0]);
		exit(0);
  	}
	else if(pid>0) //父進程執行序列
	{
		close(pipe_fd[0]); //父進程先關閉了管道的讀端
		if(write(pipe_fd[1],"Hello",5)!=-1)
			printf("parent write1 Hello!\n");
		if(write(pipe_fd[1]," Pipe",5)!=-1)
			printf("parent write2 Pipe!\n");
		close(pipe_fd[1]);
		waitpid(pid,NULL,0); /*等待子進程結束*/
		exit(0);
	}
	return 0;
}