pipe的小问题

代码是这样的
 

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

#define k 1024
#define WRITELEN (128*k)

int main()
{
    int result = -1;
    int fd[2];
    int nbytes;
    pid_t pid;
    char string[WRITELEN] = "你好，管道";
    char readbuffer[10*k];

    result = pipe(fd);
    if(-1 == result)
    {
        printf("建立管道失败 \n");
        return -1;
    }
    pid = fork();
    if(-1 == pid)
    {
        printf("fork 进程失败 \n");
        return -1;
    }
    else if(0 == pid)
    {
        int write_size = WRITELEN;
        close(fd[0]);
        while(write_size >= 0)
        {
            result = write(fd[1],string,write_size);            //好像这里出问题了，郁闷啊，谢谢各位大牛
            if(result > 0)
            {
                write_size -= result;
                printf("写入%d个字符，剩余%d个字符 \n",result,write_size);
            }
            else
            {
                sleep(10);
            }
        }
        return 0;
    }
    else
    {
        close(fd[1]);
        while(1)
        {
            nbytes = (fd[0],readbuffer,sizeof(readbuffer));

            if(nbytes <= 0)
            {
                printf("没有数据写入咯 \n");
                break;
            }
            printf("接收到%d个字符，内容是:%s \n",nbytes,readbuffer);
        }
    }
    return 0;
}