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What is the difference between square brackets and parentheses in a regex?
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/^(7|8|9)\d{9}$/
/^[789]\d{9}$/
/^[7-9]\d{9}$/
The explanation:
(a|b|c) is a regex "OR" and means "a or b or c", although the presence of brackets, necessary for the OR, also captures the digit. To be strictly equivalent, you would code (?:7|8|9) to make it a non capturing group.
[abc] is a...
What are the differences between “=” and “
What are the differences between the assignment operators = and <- in R?
7 Answers
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How to randomly select an item from a list?
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Use random.choice()
import random
foo = ['a', 'b', 'c', 'd', 'e']
print(random.choice(foo))
For cryptographically secure random choices (e.g. for generating a passphrase from a wordlist) use secrets.choice()
import secrets
foo = ['battery', 'correct', 'horse', 'staple...
How to get the command line args passed to a running process on unix/linux systems?
...proc/<pid> on Linux, just have a look.
On other Unixes things might be different. The ps command will work everywhere, the /proc stuff is OS specific. For example on AIX there is no cmdline in /proc.
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Validating email addresses using jQuery and regex
...\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]+)*|"((([ \t]*\r\n)?[ \t]+)?([\x01-\x08\x0b\x0c\x0e-\x1f\x7f\x21\x23-\x5b\x5d-\x7e\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]|\\[\x01-\x09\x0b\x0c\x0d-\x7f\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))*(([ \t]*\r\n)?[ \t]+)?")@(([a-z\d\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF...
Assigning a variable NaN in python without numpy
Most languages have a NaN constant you can use to assign a variable the value NaN. Can python do this without using numpy?
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Undefined reference to `pow' and `floor'
I'm trying to make a simple fibonacci calculator in C but when compiling gcc tells me that I'm missing the pow and floor functions. What's wrong?
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Bootstrap Dropdown menu is not working
I am having trouble getting my dropdowns to work. I can get the navbar to show up perfectly, but when I click on "Dropdown" (either of them) it does not display the dropdown menu. I have tried looking on other posts about this, but nothing that fixed everyone's problems helped. I copied the source s...
What is your preferred style for naming variables in R? [closed]
Which conventions for naming variables and functions do you favor in R code?
9 Answers
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Java 8 Streams - collect vs reduce
...duce() ? Does anyone have good, concrete examples of when it's definitely better to go one way or the other?
7 Answers
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