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Why are regular expressions so controversial? [closed]
...ions. And not just slow, but the performance of the regex engine can be totally unpredictable when faced with arbitrary (user-supplied) inputs.
– Pacerier
Dec 1 '15 at 21:53
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What does the “@” symbol mean in reference to lists in Haskell?
...hout the @, you'd have to choose between (1) or (2):(3).
This syntax actually works for any constructor; if you have data Tree a = Tree a [Tree a], then t@(Tree _ kids) gives you access to both the tree and its children.
s...
How do PHP sessions work? (not “how are they used?”)
...on files are usually stored in, say, /tmp/ on the server, and named sess_{session_id} . I have been looking at the contents and cannot figure out how they really work.
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How to convert a unix timestamp (seconds since epoch) to Ruby DateTime?
...cessary instead of DateTime. So use Time.strptime("1318996912345",'%Q').to_f and you will see the milliseconds preserved, while DateTime.strptime("1318996912345",'%Q').to_f does not preserve it.
– skensell
Feb 22 '17 at 15:20
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Extracting numbers from vectors of strings
...ion is an indirect way of getting to the solution. If you want to retrieve all the numbers, I recommend gregexpr:
matches <- regmatches(years, gregexpr("[[:digit:]]+", years))
as.numeric(unlist(matches))
If you have multiple matches in a string, this will get all of them. If you're only intere...
Equation (expression) parser with precedence?
...ursively, for example, using your sample string,
1+11*5
to do this manually, you would have to read the 1, then see the plus and start a whole new recursive parse "session" starting with 11... and make sure to parse the 11 * 5 into its own factor, yielding a parse tree with 1 + (11 * 5).
This a...
Compelling examples of custom C++ allocators?
What are some really good reasons to ditch std::allocator in favor of a custom solution? Have you run across any situations where it was absolutely necessary for correctness, performance, scalability, etc? Any really clever examples?
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Boost Statechart vs. Meta State Machine
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As there seems to be much interest, please allow me to give my (obviously biased) opinion, which should therefore be taken with a grain of salt:
MSM is much faster
MSM requires no RTTI or anything virtual
MSM has a more complete UML2 support (for example internal tr...
How to prevent vim from creating (and leaving) temporary files?
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I added this to my _vimrc file on Windows, and I'm still getting file~ files. Am I not doing something correctly?
– FilBot3
Aug 26 '15 at 14:48
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Java SE 6 vs. JRE 1.6 vs. JDK 1.6 - What do these mean?
I see many different Java terms floating around. I need to install the JDK 1.6. It was my understanding that Java 6 == Java 1.6. However, when I install Java SE 6, I get a JVM that reports as version 11.0! Who can solve the madness?
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