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How do you match only valid roman numerals with a regular expression?
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You can use the following regex for this:
^M{0,4}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})$
Breaking it down, M{0,4} specifies the thousands section and basically restrains it to between 0 and 4000. It's a relatively simple:
0: <empty> m...
How do I add a linker or compile flag in a CMake file?
...m-linux-androideabi-g++ compiler. When I try to compile a simple "Hello, World!" program it compiles fine. When I test it by adding a simple exception handling in that code it works too (after adding -fexceptions .. I guess it is disabled by default).
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How to document Python code with doxygen [closed]
I like doxygen to create documentation of C or PHP code. I have an upcoming Python project and I think I remember that Python doesn't have /* .. */ comments, and also has its own self-documentation facility which seems to be the pythonic way to document.
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Does a javascript if statement with multiple conditions test all of them?
... javascript, when using an if statement with multiple conditions to test for, does javascript test them all regardless, or will it bail before testing them all if it's already false?
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How can I update npm on Windows?
... the new best way to upgrade npm on Windows.
Run PowerShell as Administrator
Set-ExecutionPolicy Unrestricted -Scope CurrentUser -Force
npm install -g npm-windows-upgrade
npm-windows-upgrade
Note: Do not run npm i -g npm. Instead use npm-windows-upgrade to update npm going forward. Also if you r...
Difference between Math.Floor() and Math.Truncate()
What is the difference between Math.Floor() and Math.Truncate() in .NET?
12 Answers
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unix - head AND tail of file
...u can simply:
(head; tail) < file.txt
And if you need to uses pipes for some reason then like this:
cat file.txt | (head; tail)
Note: will print duplicated lines if number of lines in file.txt is smaller than default lines of head + default lines of tail.
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When should we use intern method of String on String literals
According to String#intern() , intern method is supposed to return the String from the String pool if the String is found in String pool, otherwise a new string object will be added in String pool and the reference of this String is returned.
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How to find all occurrences of a substring?
...There is no simple built-in string function that does what you're looking for, but you could use the more powerful regular expressions:
import re
[m.start() for m in re.finditer('test', 'test test test test')]
#[0, 5, 10, 15]
If you want to find overlapping matches, lookahead will do that:
[m.st...
What is the use of ObservableCollection in .net?
...event handler to do some additional processing. This may be changing a UI or performing some other operation.
The code below doesn't really do anything but demonstrates how you'd attach a handler in a class and then use the event args to react in some way to the changes. WPF already has many oper...