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How to extract numbers from a string and get an array of ints?
...p = Pattern.compile("-?\\d+");
Matcher m = p.matcher("There are more than -2 and less than 12 numbers here");
while (m.find()) {
System.out.println(m.group());
}
... prints -2 and 12.
-? matches a leading negative sign -- optionally. \d matches a digit, and we need to write \ as \\ in a Java ...
echo that outputs to stderr
...
You could do this, which facilitates reading:
>&2 echo "error"
>&2 copies file descriptor #2 to file descriptor #1. Therefore, after this redirection is performed, both file descriptors will refer to the same file: the one file descriptor #2 was originally referri...
Which is faster: while(1) or while(2)?
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23 Answers
23
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Pairs from single list
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52
My favorite way to do it:
from itertools import izip
def pairwise(t):
it = iter(t)
ret...
Immutable vs Mutable types
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233
What? Floats are immutable? But can't I do
x = 5.0
x += 7.0
print x # 12.0
Doesn't that "mu...
Testing whether a value is odd or even
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22 Answers
22
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Python Dictionary Comprehension
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528
There are dictionary comprehensions in Python 2.7+, but they don't work quite the way you're tr...
What is the most efficient/elegant way to parse a flat table into a tree?
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462
Now that MySQL 8.0 supports recursive queries, we can say that all popular SQL databases support...
How can I match a string with a regex in Bash?
...ite a bash script that contains a function so when given a .tar , .tar.bz2 , .tar.gz etc. file it uses tar with the relevant switches to decompress the file.
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How do I use .toLocaleTimeString() without displaying seconds?
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325
You can always set the options, based on this page you can set, to get rid of the seconds, some...