tell Returns the current position *in bytes* for FILEHANDLE 非常感谢
On 8月9日, 上午2时20分, Anthony WU <[email protected]> wrote: > my $tmp; > open (my $fp, '+<', 'filename'); > binmode ($fp); > read ($fp, $tmp, 0x8f); > ................. > seek ($fp, 0xb0, 0); > read ($fp, $tmp, (-s $fp) - tell ($fp)); > ................. > close ($fp); > > > > -------- Original Message -------- > Subject: [PerlChina] Re: 16进制文件操作 > From: perlw01f <[email protected]> > To: PerlChina Mongers 讨论组 <[email protected]> > Date: 8/8/2009 23:51 > > 接问一句 如何 读取 0x00-0x8f ？ > > 我先 binmode 再 read 貌似不好使？ > > >> On 8月8日, 下午7时24分, Anthony WU <[email protected]> wrote:> 我把 seek 第二 > >> 及第三個參數寫反了，刪除是不能的，但你可以通過 先讀 > > >>> 0x00-0x8f 跳到0xb0再讀到EOF並把所取得的BYTES寫到新檔案 > > >>> -------- Original Message -------- > >>> Subject: [PerlChina] Re: 16进制文件操作 > >>> From: perlw01f <[email protected]> > >>> To: PerlChina Mongers 讨论组 <[email protected]> > >>> Date: 8/8/2009 10:42 > > >>>> 谢谢 > >>>> perldoc -f seek的结论貌似跟这个不一样 ？ > > >>>> seek FILEHANDLE,POSITION,WHENCE > >>>> Sets FILEHANDLE's position, just like the "fseek" call of > >>>> "stdio". FILEHANDLE may be an expression whose value gives > >>>> the > >>>> name of the filehandle. The values for WHENCE are 0 to set > >>>> the > >>>> new position *in bytes* to POSITION, 1 to set it to the > >>>> current > >>>> position plus POSITION, and 2 to set it to EOF plus POSITION > >>>> (typically negative). For WHENCE you may use the constants > >>>> "SEEK_SET", "SEEK_CUR", and "SEEK_END" (start of the file, > >>>> current position, end of the file) from the Fcntl module. > >>>> Returns 1 upon success, 0 otherwise. > > >>>> Note the *in bytes*: even if the filehandle has been set to > >>>> operate on characters (for example by using the ":utf8" open > >>>> layer), tell() will return byte offsets, not character > >>>> offsets > >>>> (because implementing that would render seek() and tell() > >>>> rather > >>>> slow). > > >>>> If you want to position file for "sysread" or "syswrite", > >>>> don't > >>>> use "seek"--buffering makes its effect on the file's system > >>>> position unpredictable and non-portable. Use "sysseek" > >>>> instead. > > >>>> Due to the rules and rigors of ANSI C, on some systems you > >>>> have > >>>> to do a seek whenever you switch between reading and > >>>> writing. > >>>> Amongst other things, this may have the effect of calling > >>>> stdio's clearerr(3). A WHENCE of 1 ("SEEK_CUR") is useful > >>>> for > >>>> not moving the file position: > > >>>> seek(TEST,0,1); > > >>>> This is also useful for applications emulating "tail -f". > >>>> Once > >>>> you hit EOF on your read, and then sleep for a while, you > >>>> might > >>>> have to stick in a seek() to reset things. The "seek" > >>>> doesn't > >>>> change the current position, but it *does* clear the end-of- > >>>> file > >>>> condition on the handle, so that the next "<FILE>" makes > >>>> Perl > >>>> try again to read something. We hope. > > >>>> If that doesn't work (some IO implementations are > >>>> particularly > >>>> cantankerous), then you may need something more like this: > > >>>> for (;;) { > >>>> for ($curpos = tell(FILE); $_ = <FILE>; > >>>> $curpos = tell(FILE)) { > >>>> # search for some stuff and put it into files > >>>> } > >>>> sleep($for_a_while); > >>>> seek(FILE, $curpos, 0); > >>>> } > > >>>> 另外，您的code 我尝试了一下 > >>>> seek ($fp, 0, 0x80); > >>>> print $fp "\x0"; > >>>> 实际的效果是 00000000h这一行 第1和2字节变成了0 没有偏移？ > >>>> 我自己尝试 > >>>> seek ($fp, 16*8, 0x00); > >>>> print $fp "\x0"; > >>>> 可以达到目的 > > >>>> 另外 我想请教 如何删除掉一部分内容呢 比如 0x90-0xb0 > >>>> 谢谢 > >>>> On 8月8日, 上午12时48分, Anthony WU <[email protected]> wrote: > > >>>>> 以你所說的操作大約是 > >>>>> open (my $fp, '+<', 'x.dat'); > >>>>> binmode ($fp); > >>>>> seek ($fp, 0, 0x80); > >>>>> print $fp "\x0"; > >>>>> seek ($fp, 0, 0x82); > >>>>> print $fp "\x0"; > >>>>> seek ($fp, 0, 0x84); > >>>>> print $fp "\x0"; > >>>>> seek ($fp, 0, 0x86); > >>>>> print $fp "\x8B"; > >>>>> seek ($fp, 0, 0x87); > >>>>> print $fp "\x8B"; > >>>>> seek ($fp, 0, 0x88); > >>>>> print $fp "\x0A"; > >>>>> seek ($fp, 0, 0x89); > >>>>> print $fp "\x0A"; > >>>>> .... > >>>>> .... > >>>>> .... > >>>>> close ($fp); > > >>>>> -------- Original Message -------- > >>>>> Subject: [PerlChina] Re: 16进制文件操作 > >>>>> From: perlw01f <[email protected]> > >>>>> To: PerlChina Mongers 讨论组 <[email protected]> > >>>>> Date: 7/8/2009 21:16 > > >>>>>> 都是在确定的位置 > > >>>>>> 如 00000080h 这一栏 第1 3 5 字节换为0 78换为8B 9 10 换为0A 还有一些其他的 > > >>>>>> On 8月7日, 下午9时04分, Anthony WU <[email protected]> wrote: > > >>>>>>> 你的字節是定位修改的嗎？有什麼規律的？ > > >>>>>>> -------- Original Message -------- > >>>>>>> Subject: [PerlChina] Re: 16进制文件操作 > >>>>>>> From: perlw01f <[email protected]> > >>>>>>> To: PerlChina Mongers 讨论组 <[email protected]> > >>>>>>> Date: 7/8/2009 20:56 > > >>>>>>>> 我有一个文件 x.dat，由x.rar.gz压缩而成 但是其中某些字节做了修改处理 现在的文件名是 a.dat > >>>>>>>> 现在 我想逆行操作，即 > >>>>>>>> 先将a.date rename成x.rar.gz 然后利用ue修改某些字节 之后才能解压缩成x.date > > >>>>>>>> 由于文件数量较多 且ue 16进制 修改也不是很方便 > >>>>>>>> 所以想 用 perl实现 > >>>>>>>> 谢谢 > > >>>>>>>> On 8月7日, 下午5时17分, cnhack TNT <[email protected]> wrote: > > >>>>>>>>> 能举例说明你要做的事情么？ > > >>>>>>>>> 2009/8/7 perlw01f <[email protected]> > > >>>>>>>>>> perl中 有没有类似ultredit中那种直接转换成16进制进行操作的方法或者module > > >>>>>>>>>> unpack是不是太费事了 > > >>>>>>> -- > >>>>>>> Best Regards, > >>>>>>> Anthony WU > > >>>>> -- > >>>>> Best Regards, > >>>>> Anthony WU > > >>> -- > >>> Best Regards, > >>> Anthony WU > > -- > Best Regards, > Anthony WU --~--~---------~--~----~------------~-------~--~----~ 您收到此信息是由于您订阅了 Google 论坛“PerlChina Mongers 讨论组”论坛。 要在此论坛发帖，请发电子邮件到 [email protected] 要退订此论坛，请发邮件至 [email protected] 更多选项，请通过 http://groups.google.com/group/perlchina?hl=zh-CN 访问该论坛 -~----------~----~----~----~------~----~------~--~---
