best way to modify a file

[dornick]

Is there any way to do this without simply rewriting the entire file
with the changes? I was thinking of using fstream, since it can handle
input and output, but couldn't figure out exactly how to do it.

Suggestions?

Thanks,
dornick

 

[DHOLLINGSWORTH2]

Is there any way to do this without simply rewriting the entire file
with the changes? I was thinking of using fstream, since it can handle
input and output, but couldn't figure out exactly how to do it.

Suggestions?

Thanks,
dornick

You can open a file to "rw", which will allow you to make changes. However,
if you are inserting text, then the portion of the file occuring after the
change would be over written. AS long as you are replacing say a char with
a different char this is ok. Otherwise you will need to read ahead of your
write, and re-write the intire end of the file.

 

[Larry Brasfield]

You can open a file to "rw", which will allow you to make changes. However, if you are inserting text, then the portion of the
file occuring after the change would be over written. AS long as you are replacing say a char with a different char this is ok.
Otherwise you will need to read ahead of your write, and re-write the intire end of the file.

That suggestion should be followed with some
caution and a caveat. For characters that are
not subject to line-boundary translations, it
will work. But if the stream is opened in text
mode, (usually the default), be aware that for
each such character written, more than one
byte could be written and that for each such
character overwritten with a plain character,
the result could be the plain character value
followed by a portion of the line-boundary
sequence used on the system.

For those reasons, I would tend to not try
to exploit the suggestion.

 

[dornick]

Thanks for the suggestion. I am, in fact, only trying to replace
individual characters. If you don't mind, could you give me a few
lines of code to show me exactly how to pull this off? I would be very
grateful.

dornick

 

[Default User]

Thanks for the suggestion. I am, in fact, only trying to replace
individual characters. If you don't mind, could you give me a few
lines of code to show me exactly how to pull this off? I would be very
grateful.

Would you mind quoting a reasonable portion of the post to which you
are replying, so that people can tell:

1. Who you are addressing
2. What you are talking about

I would be very grateful. To do this via Google, click "show options"
and use the Reply found there, NOT the one at the bottom of the post.



Brian

 

[Larry Brasfield]

Read about the "fseek()", "lseek()", and "seek()" in the C runtime,
or the "seekpos()" and "seekoff()" members of std::basic_filebuf
in the C++ standard library.

I presume you are not concerned about rewriting
characters that may become, or already be, line
boundary characters.

Would you mind quoting a reasonable portion of the post to which you
are replying, so that people can tell:

1. Who you are addressing
2. What you are talking about

I would be very grateful. To do this via Google, click "show options"
and use the Reply found there, NOT the one at the bottom of the post.

Most newsreader tools have a thread view, aka
"Group by Conversation" in MS Outlook Express.
This relies upon the "References" and "Message-ID"
fields to show what post is in reply to what.

That said, selective quoting is a real courtesy.

 

[Default User]

Most newsreader tools have a thread view, aka
"Group by Conversation" in MS Outlook Express.
This relies upon the "References" and "Message-ID"
fields to show what post is in reply to what.

And many people using those newsreaders have their options set to show
only new messages. It's ridiculous to require people to go back and
read old message to figure our what someone is talking about.

That said, selective quoting is a real courtesy.

It's more than a courtesy, it's been the standard of usenet for a long
time. I have no idea what got into the Google people that they screwed
this up so badly.


Brian

 

[dornick]

Would you mind quoting a reasonable portion of the post to which you
are replying, so that people can tell:

1. Who you are addressing
2. What you are talking about

I would be very grateful. To do this via Google, click "show options"
and use the Reply found there, NOT the one at the bottom of the post.



Brian

Thanks for the help. I guess Google had me spoiled with all their
"conversation" views and I forgot some people would have no context for
my post.

 

[Default User]

Default User wrote:

Thanks for the help. I guess Google had me spoiled with all their
"conversation" views and I forgot some people would have no context for
my post.

You're welcome, and thank you for understanding.



Brian