how is the "find" algorithm in text editors constructed?

[zskillz]

I'm going to have to write a program that parses through a very large text file looking for an instance of a specific word....

in the past, I've just read it line by line, and searched each token for a match to what I want... however, this seems like it'd be really really slow. So I'm curious how programs like wordpad/notepad, etc. do it. I feel like I could really cut down on a lot of wasted time if I could mimic that implementation...

so I'm looking for suggestions or any sort of help that you have to offer!

thanks in advance,
-Z

[SpookyEddy]

I would select your open source text editor of choice, grab its source code and have a quick look how they implement search functions. I had a quick check and vim, emacs and nano all have a search.c that should give you some ideas, link lists seem to be mentioned.

Regards

ed

[pedantic]

Quote:

however, this seems like it'd be really really slow.

was it really slow in the past? like, when you did it?

text editors simply search the string/stream/char_array that is in memory. no reason for file/io, just memory search.

[Nighthawk]

It depends on the language you're using. I think the way I'd do it is to write it in Perl using a regular expression and make it into a module.. I'm not sure whether other languages have regexp or not.

[zskillz]

So I'm doing this in java right now, but I'll probably convert it to C or C++ (more likely) in the future.

The files that I'm going to be searching through are going to be multiple thousands of lines of code... possibly up to 100k+ lines. (these are the output files of electronic structure calculations on various molecules). The output is so long because this technique is a self-consistant field (SCF) calculation, so it takes the results from the current run - prints them - then reinserts them into the new run. These repeats until the convergence tolerence is reached....

anyway... it's sort of beside the point. I'm looking for a way to rip a chunk of the output from the code (the final output actual) and then I'll be doing calculations based on the output that I take....

I was just hoping to find a faster/more efficient way to get to the information that I want then going line by line through these gigantic files.

any other ideas are invited and appreciated.

thanks
-Z

[pedantic]

Quote:

any other ideas are invited and appreciated.

except mine...

Quote:

I was just hoping to find a faster/more efficient way to get to the information that I want then going line by line through these gigantic files.

[VHockey86]

Try searching the web for source code on "find" functions