Currently there is no way to select all empty cells in given range.
^$ regexp in Find and Replace should find them, but it was intentionally disabled in some historical OOo release due to "performance issues" .
There are two things that should be considered:
1. Does these "performance issues" still apply on any fairly new hardware?
2. Can we safely assume, that user that does use regular expressions KNOWS what he is doing? I think that LO is a tool and should not think instead of user. If user wants to run resource-hungry query on large dataset, then he should be able to do it (and face performance penalty, if they applies).
It's an interesting thought. In some sense the empty cells don't really exist - at least, in general we try to ensure they do not (there used to be some exceptions for 'notes' and also the empty source cells for dependencies ie. do =A3 in A1 and A3 will have an invisible cell backing but these are filtered out too it seems).
If you'd like to hack this - it shouldn't be -too- hard. I suspect we want to run the regexp on a single empty string the first time we hit an empty cell and then do some rather more optimised selection building - which (you might hope) should be reasonably efficient.
But of course all that needs some hacking input I expect :-) the place to go is:
sc/source/core/data/table6.cxx which shouldn't look (so) frightening I hope.
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I would like to try this one.
(In reply to Mohammed Abdul Azeem from comment #6)
> I would like to try this one.
You are welcome, assign it to yourself, and follow our step by step guide:
Mohammed Abdul Azeem committed a patch related to this issue.
It has been pushed to "master":
tdf#57523 - Regex search "^$" finds all empty cells in given range.
It will be available in 5.2.0.
The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.