#include <errno.h>

#include <fcntl.h>

#include <unistd.h>

#include <stdio.h>

int main(int argc,char* argv[])

{

    int fprcw[];            //for parent read,child write

    int fpwcr[];

    char str[];

    pid_t pid;

    if(pipe(fprcw) == -)

    {

        perror("pipe1");

        return -;

    }

    if(pipe(fpwcr) == -)

    {

        perror("pipe2");

        close(fprcw[]);

        close(fpwcr[]);

        return -;

    }

    pid = fork();

    if(pid == )

    {

        close(fprcw[]);

        close(fpwcr[]);

        sleep();

        write(fprcw[],"hello world!",);

        read(fpwcr[],str,);

        printf("child str is:%s\n",str);

        close(fpwcr[]);

        close(fprcw[]);

    }

    else if(pid > )

    {

        close(fpwcr[]);

        close(fprcw[]);

        write(fpwcr[],"how are you!",);

        if(waitpid(pid,NULL,) == -)

        {

            perror("waitpid");

        }

        read(fprcw[],str,);

        printf("parent str is: %s\n",str);

        close(fpwcr[]);

        close(fprcw[]);

    }

    else

    {

        perror("fork");

    }

    return ;

}