LINUX下用C语言历遍目录 C语言列出目录2007-04-06 21:02功能：       Linux下C语言目录历遍 (读取目录)

作者：       小徐

QQ:          339534039

转载请注明出处

呵呵，LINUX下历遍目录的方法一般是这样的

打开目录-》读取-》关闭目录

相关函数是

opendir -> readdir -> closedir

#include <dirent.h>

DIR *opendir(const char *dirname);

#include <dirent.h>

struct dirent *readdir(DIR *dirp);

#include <dirent.h>

int closedir(DIR *dirp);

好了，三个函数都出来了呵呵，原型就是上面，给自己解释一下免得以后我自己忘了呵呵！我以经忘过好几回了，所以这次放上博客来

opendir用于打开目录，是类似于流的那种方式，返回一个指向DIR结构体的指针他的参数*dirname是一个字符数组或者字符串常量,

readdir函数用于读取目录，他只有一个参数，这个参数主opendir返回的结构体指针，或者叫句柄更容易理解些吧。这个函数也返回一个结构 体指针 dirent *

dirent的结构如下定义

    struct dirent

    {

        long d_ino;                      /* inode number */

        off_t d_off;                     /* offset to this dirent */

        unsigned short d_reclen;         /* length of this d_name */

        char d_name [NAME_MAX+1];        /* file name (null-terminated) */

    }

结构体中d_ino存放的是该文件的结点数目，什么是结点数目呢我也说不清楚了呵呵，查一下其它资料了

d_off 是文件在目录中的编移，具体是什么意思我也不是很明白，我很少用到它，其本上就是用到d_name short d_reclen是这个文件的长度，需要注意的是这里的长度并不是指文件大小，因为大小和长度是2回事了，你可以用lseek将文件长度移得很长，但大小 其实还是那么大.最后一个元素就是我们要的了，文件名称！

写了一个实例:

/**

* 功能：       Linux下C语言目录历遍 (读取目录)

* 作者：       小徐

* 邮箱：      xjtdy888@163.com

* QQ:          339534039

* 转载请注明出处

*/

#include <stdio.h>

#include <stdlib.h>

#include <sys/types.h>

#include <unistd.h>

#include <dirent.h>

void print_usage(void);

void print_usage(void)

{

printf("Usage: test dirname\n");

}

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

{

DIR * dp;

struct dirent *filename;

if (argc < 2)

{

       print_usage();

       exit(1);

}

dp = opendir(argv[1]);

if (!dp)

{

       fprintf(stderr,"open directory error\n");

       return 0;

}

while (filename=readdir(dp))

{

       printf("filename:%-10s\td_info:%ld\t d_reclen:%us\n",

         filename->d_name,filename->d_ino,filename->d_reclen);

}

closedir(dp);

return 0;

}

将上面代码保存为readdir.c执行下面的命令进行编译测试

[root@phpos ~]# gcc readdir.c

[root@phpos ~]# ./a.out

Usage: test dirname

[root@phpos ~]# ./a.out /etc/samba/

filename:lmhosts             d_info:49296          d_reclen:24s

filename:smb.conf            d_info:49825          d_reclen:24s

filename:smbpasswd           d_info:49402          d_reclen:24s

filename:..                  d_info:47906          d_reclen:16s

filename:secrets.tdb         d_info:49812          d_reclen:24s

filename:.                   d_info:49295          d_reclen:16s

filename:smbusers            d_info:49377          d_reclen:24s

[root@phpos ~]# ./a.out /var/

filename:preserve            d_info:31971          d_reclen:24s

filename:lock                d_info:31966          d_reclen:16s

filename:yp                  d_info:31976          d_reclen:16s

filename:empty               d_info:31962          d_reclen:24s

filename:run                 d_info:31972          d_reclen:16s

filename:lib                 d_info:31939          d_reclen:16s

filename:nis                 d_info:31969          d_reclen:16s

filename:local               d_info:31965          d_reclen:24s

filename:spool               d_info:31973          d_reclen:24s

filename:tmp                 d_info:31941          d_reclen:16s

filename:opt                 d_info:31970          d_reclen:16s

filename:log                 d_info:31959          d_reclen:16s

filename:crash               d_info:31997          d_reclen:24s

filename:..                  d_info:2              d_reclen:16s

filename:account             d_info:32037          d_reclen:24s

filename:mail                d_info:31968          d_reclen:16s

filename:cache               d_info:31960          d_reclen:24s

filename:db                  d_info:31961          d_reclen:16s

filename:.                   d_info:31938          d_reclen:16s

[root@phpos ~]#

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