Read file bottom up

[Samant.Trupti@gmail.com]

I need to read a huge file. The content that I want to read are
somewhere at the bottom. Can anyone please let me know a way to read
the file bottom up?
Thanks
Trupti

[Jeff Schwab]

Re: Read file bottom up

Samant.Trupti@g mail.com wrote:

I need to read a huge file. The content that I want to read are
somewhere at the bottom. Can anyone please let me know a way to read
the file bottom up?

Take a look at the istream::seekg method. It will let you position the
file-pointer at an arbitrary place in the input stream.

[sean_in_raleigh@yahoo.com]

Re: Read file bottom up

On Feb 18, 9:29 am, "Samant.Tru...@ gmail.com"
<Samant.Tru...@ gmail.comwrote:

I need to read a huge file. The content that I want to read are
somewhere at the bottom. Can anyone please let me know a way to read
the file bottom up?
Thanks
Trupti

$ tail my_huge_file.tx t

If that's not suitable for your environment, you
should provide some details on that.

Sean

[peter koch]

Re: Read file bottom up

On 18 Feb., 17:42, Jeff Schwab <j...@schwabcen ter.comwrote:

Samant.Tru...@g mail.com wrote:

I need to read a huge file.  The content that I want to read are
somewhere at the bottom.  Can anyone please let me know a way to read
the file bottom up?

>
Take a look at the istream::seekg method.  It will let you position the
file-pointer at an arbitrary place in the input stream.

No it will not. seek will only (portably) position you somewhere where
you have been before.

/Peter

[peter koch]

Re: Read file bottom up

On 18 Feb., 18:00, sean_in_rale... @yahoo.com wrote:

On Feb 18, 9:29 am, "Samant.Tru...@ gmail.com"
>
<Samant.Tru...@ gmail.comwrote:

I need to read a huge file.  The content that I want to read are
somewhere at the bottom.  Can anyone please let me know a way to read
the file bottom up?
Thanks
Trupti

>
 $ tail my_huge_file.tx t
>
If that's not suitable for your environment, you
should provide some details on that.
>
Sean

tail is not appropriate as it is not portable, not C++ and not generic
(tail is for text-files only).

/Peter

[Jeff Schwab]

Re: Read file bottom up

peter koch wrote:

On 18 Feb., 17:42, Jeff Schwab <j...@schwabcen ter.comwrote:

>Samant.Tru...@ gmail.com wrote:

>>I need to read a huge file. The content that I want to read are
>>somewhere at the bottom. Can anyone please let me know a way to read
>>the file bottom up?

>Take a look at the istream::seekg method. It will let you position the
>file-pointer at an arbitrary place in the input stream.

>
No it will not. seek will only (portably) position you somewhere where
you have been before.

According to what? I'm looking at the draft standard for 0x, and don't
see anything like that. The seekg method can fail, but I don't see
anything magical about "where you have been before."

[guinness.tony@gmail.com]

Re: Read file bottom up

On 22 Feb, 10:02, guinness.t...@g mail.com wrote:

>
    std::ifstream file( "myfile.dat ", std::ios_base:: binary );
>
    file.seekg( 0, std::ios_base:: end );
    std::streampos const endpos = file.tellg();
    file.seekg( 0, std::ios_base:: beg );
    std::streamoff const file_length = file.tellg() - endpos;

// Aaagh!
std::streamoff const file_length = endpos - file.tellg();

--
Tony

[guinness.tony@gmail.com]

Re: Read file bottom up

On 22 Feb, 15:59, James Kanze <james.ka...@gm ail.comwrote:

Table 88 in 27.4.3.2 indicates that a distance (streamoff) can
be obtained by subtracting one streampos from another.
Although I can't find it explicitly stated, usage (and one of
the footnotes) imply to me that streamoff is integral.

>
Which footnote?

I think I must have been referring to footnote 174)
(in 17.4.4.7): "... types described as synonyms for
basic integral types, such as ... streamoff."

--
Tony