菜鸟问个关于fork的问题

#include <stdio.h>

#include <unistd.h>

#define BUFSIZE 100

int main()

{

	int n;

	int fd[2];

	pid_t pid;

	char buf[BUFSIZE];

	if(pipe(fd)<0)

		printf("pipe errorn");

	if(pid=fork()<0)

		printf("fork errorn");

	if (pid>0)/*parent*/

	{

		close(fd[0]);

		printf("this is parent process");

		write(fd[1],"Hello world",12);

	}

	if(pid==0) /*child*/

	{

		//sleep(1);

		printf("this is child process");

		close(fd[1]);

		n=read(fd[0],buf,BUFSIZE);

		write(STDOUT_FILENO,buf,n);

	}

	return 0;

}