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What is the 'instanceof' operator used for in Java?
...);,
animal instanceof Dog // false
because Animal is a supertype of Dog and possibly less "refined".
And,
dog instanceof Cat // does not even compile!
This is because Dog is neither a subtype nor a supertype of Cat, and it also does not implement it.
Note that the variable used for dog above...
What is a Context Free Grammar?
...to me what a context free grammar is? After looking at the Wikipedia entry and then the Wikipedia entry on formal grammar, I am left utterly and totally befuddled. Would someone be so kind as to explain what these things are?
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Code Golf - π day
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In dc: 88 and 93 93 94 96 102 105 129 138 141 chars
Just in case, I am using OpenBSD and some supposedly non-portable extensions at this point.
93 chars. This is based on same formula as FORTRAN solution (slightly different results t...
C# DateTime to “YYYYMMDDHHMMSS” format
...M = months, h = 12 hour, H = 24 hour. I suspect someone started with time and said hms = hours mins seconds, then H became 24 hour and then they got to date and ran out of unique letters so went with case. Just one of those things.
– Douglas Anderson
May 23 '...
How to do a simple file search in cmd
...search for a file given its name or part of its name, from the windows command line (not power shell). This is similar to opening explorer and using the search box at the top.
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“User interaction is not allowed” trying to sign an OSX app using codesign
.../thread/311971. Thanks ashish agrawal!
Login your build user via the GUI and open Keychain Access. Select your signing private key, right-click, choose Get Info, change to the Access Control tab and select the "Allow all applications to access this item".
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How to 'bulk update' with Django?
...it must be on an original QuerySet so you'll need to lean on the .filter() and .exclude() methods.
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Expert R users, what's in your .Rprofile? [closed]
I have always found startup profile files of other people both useful and instructive about the language. Moreover, while I have some customization for Bash and Vim , I have nothing for R.
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Create a git patch from the uncommitted changes in the current working directory
...anges.
git diff --cached for staged changes.
git diff HEAD for both staged and unstaged changes.
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Process escape sequences in a string in Python
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hands down, the best solution! btw, by docs it should be "string_escape" (with underscore) but for some reason accepts anything in the pattern 'string escape', 'string@escape" and whatnot... basically 'string\W+escape'
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