Re: Recurse folders - Great Code
- From: Ulrich Korndoerfer <ulrich_wants_nospam@xxxxxxxxxxxx>
- Date: Sun, 04 Feb 2007 04:46:28 +0100
Hi Don,
Don schrieb:
...
Just tried it. Even more impressed now. Your class works great. I
only encountered one problem and that was when I tried searching my
entire drive. Nothing showed up in the results text box (and no error
message) so I used a Rich Textbox instead, thinking maybe there was
too much text, and that did the trick. On the other hand, maybe I
was impatient and didn't wait long enough for results, but your code
does run fast - and with so little code for the user to have to mess
with. I like it.
Collecting all files on a drive may take some time. This is due to the amount of files and to the OS calls which have to scan the whole drive. My class does this as fast as eg. Windows Explorer in a search would do.
If you have waited long enough (the command button's caption reverts to "Start search" from "Searching..."), there should be output in the text box, even if no files were found (then "No files found" is output).
And remember, even if no files are found because your file name filter excludes them all (say using "abcd.gfh" as filter which would only find files of that name), the search is not much faster than a search returning *all* files. That is because we always have to scan all directories (that is read the dirs content) to be sure we do not overlook a file.
With the Rich Textbox I can also do more with the resulting text
output.
That's fine. The class stores the search's result internally and it is up to you which parts of the search (eg file names only, dirs only, file attributes etc) you will print out in the GUI and which control you will use for this. Indeed the rich text box is more accomodated for big amounts of text, but also adds overhead to the text data.
After a search, as long you hold a reference to the class instance that did the search, all the data is available and you can query the data eg. many times under different aspects.
I noticed when run a second time, it's VERY fast. I'm assuming the
result of caching, but now I'm more interested in expanding what this
can do for me.
Yes, this caching is done by Windows for you. You will see the same effect when doing a search using windows Explorer. A second run always is significantly faster. However when using my class it is not necessary to do a second run, as all the data gathered from the first run is still there.
If you are eg searching for many different files (having different names or extensions), your best bet is to do a search including *all* files (using "*" as file name filter) and then just extract the files you are interested in. The class holds the data for all files in memory (even if there are tens of thousands or hundreds of thousands) and you can search them now from memory, which is much faster (even when taking into account that the system does caching) as to start a new search for each files of interest.
I can see a lot can be done with this. When I get a chance I'll have
to review the source code as you mentioned. I'm no pro at programming
but I should get a pretty good education from this. I'm pretty new at
working with API functions. This is the first time I added a class
file to an application.
Now you could see how easy classes make working with difficult functionality. The class encapsulates all that stuff (hides its inner workings) and gives you some handy, simple methods to get your work done. You should use classes more often :-)
--
Ulrich Korndoerfer
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