From: http://blog.163.com/xychenbaihu@yeah/blog/static/1322296552011625112831213/

文件指针---->文件描述符:                          //   fp ----> fd

FILE *fp = NULL;

fp  = fopen("/home/billchen/test.txt","r");               //得到文件描述符

if (fp == NULL)

{

           perror("open file error:");

           exit(1);

}

else

{

           //成功

}

将fp转换成文件描述符:

int   fd ;

fd  =  fileno(fp);

文件描述符---->文件指针:                          //   fd---->fp

int  fd;

fd   =  open("/home/billchen/test.txt",O_CREAT|O_RDWR,0666);

if ( fd == -1 )

{

          perror("open file error:");

          exit(1);

}

else

{

          //成功

}

将fd转换成文件指针:

FILE *fp = NULL;

fp = fdopen(fd);

=============================================================================================

总结：

int fd;

FILE *fp;

fd = fileno(fp);

fp = fdopen(fd, "r");