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Validating IPv4 addresses with regexp
I've been trying to get an efficient regex for IPv4 validation, but without much luck. It seemed at one point I had had it with (25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?(\.|$)){4} , but it produces some strange results:
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Why does C++ not allow inherited friendship?
Why is friendship not at least optionally inheritable in C++? I understand transitivity and reflexivity being forbidden for obvious reasons (I say this only to head off simple FAQ quote answers), but the lack of something along the lines of virtual friend class Foo; puzzles me. Does anyone know ...
Static variables in JavaScript
How can I create static variables in Javascript?
42 Answers
42
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Case conventions on element names?
...tend to use lower case with hyphens.
There is a philosophical distinction between seeing XML as a format for platform neutral documents, which W3C standards try to encourage, and languages such as XAML which see XML as a serialisation of a platform specific object graph.
If you're not using XML as...
How to filter Pandas dataframe using 'in' and 'not in' like in SQL
...to_keep)
0 False
1 True
2 False
3 True
Name: country, dtype: bool
>>> df[df.country.isin(countries_to_keep)]
country
1 UK
3 China
>>> df[~df.country.isin(countries_to_keep)]
country
0 US
2 Germany
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Fastest way to check if a string matches a regexp in ruby?
... is the fastest way to check if a string matches a regular expression in Ruby?
7 Answers
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How to insert an item into an array at a specific index (JavaScript)?
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What you want is the splice function on the native array object.
arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert).
In this example we will create an array and add an element to it into index 2:
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PHPUnit: assert two arrays are equal, but order of elements not important
What is a good way to assert that two arrays of objects are equal, when the order of the elements in the array is unimportant, or even subject to change?
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Make copy of an array
I have an array a which is constantly being updated. Let's say a = [1,2,3,4,5] . I need to make an exact duplicate copy of a and call it b . If a were to change to [6,7,8,9,10] , b should still be [1,2,3,4,5] . What is the best way to do this? I tried a for loop like:
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What is the optimal Jewish toenail cutting algorithm?
...simply put their feet in it and run it instead of having to manually do it by biting them or using nail clippers.
6 Answers...