apue note1-about DIR

#include <stdio.h>
#include <dirent.h>

int main(int argc,char* argv[])
{
    DIR             *dp;
    struct dirent   *dirp;
    unsigned char   c='d';
    int             i=0, offset=0;

    if(argc != 2)
    {
        perror("please input directory!");
        return 1;
    }
    if((dp = opendir(argv[1])) == NULL)
    {
        perror("can't open /home");
        return 1;
    }
    while((dirp = readdir(dp)) != NULL)
    {
        #if 0
        printf("%ld--",dirp->d_ino);
        printf("%u--",dirp->d_reclen);
        printf("%d--",dirp->d_off);
        #endif
        i++;
        if(1 == i)
            offset =  telldir(dp);
        printf("%d:%s\n",i,dirp->d_name);
    } //到此目录流已经结束
    printf("end\n");

    rewinddir(dp);//将目录流返回到开始处

    printf("again\n");
    while((dirp = readdir(dp)) != NULL)
    {
         printf("%s\n",dirp->d_name);
    }

    printf("this is telldir ,seekdir:\n");

    seekdir(dp,offset);//将目录流定位到之前telldir的位置处，然后调用readdir向后读取

    while((dirp = readdir(dp)) != NULL)
    {
        #if 0
        printf("%ld--",dirp->d_ino);
        printf("%u--",dirp->d_reclen);
        printf("%d--",dirp->d_off);
        #endif
        printf("%s\n",dirp->d_name);
    }

    closedir(dp);

    return 0;
}