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Why is this F# code so slow?
...es generic comparison (I thought this uses just IComparable, but it is actually more complicated - it would use structural comparison for F# types and it's fairly complex logic).
> let min3(a, b, c) = min a (min b c);;
val min3 : 'a * 'a * 'a -> 'a when 'a : comparison
In the C# version, ...
Regex, every non-alphanumeric character except white space or colon
...
[^a-zA-Z\d\s:]
\d - numeric class
\s - whitespace
a-zA-Z - matches all the letters
^ - negates them all - so you get - non numeric chars, non spaces and non colons
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Merge Images Side by Side(Horizontally)
...hips with the montage utility. Montage will append each image side-by-side allowing you to adjust spacing between each image (-geometry), and the general layout (-tile).
montage [0-5].png -tile 5x1 -geometry +0+0 out.png
Other examples can be found on Montage Usage page
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PHP - Move a file into a different folder on the server
I need to allow users on my website to delete their images off the server after they have uploaded them if they no longer want them. I was previously using the unlink function in PHP but have since been told that this can be quite risky and a security issue. (Previous code below:)
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How do I get the result of a command in a variable in windows?
...
If you have to capture all the command output you can use a batch like this:
@ECHO OFF
IF NOT "%1"=="" GOTO ADDV
SET VAR=
FOR /F %%I IN ('DIR *.TXT /B /O:D') DO CALL %0 %%I
SET VAR
GOTO END
:ADDV
SET VAR=%VAR%!%1
:END
All output lines are stor...
How to get the original value of an attribute in Rails
is there a way to get the original value that an ActiveRecord attribute (=the value that was loaded from the database)?
4 A...
How to use base class's constructors and assignment operator in C++?
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You can explicitly call constructors and assignment operators:
class Base {
//...
public:
Base(const Base&) { /*...*/ }
Base& operator=(const Base&) { /*...*/ }
};
class Derived : public Base
{
int additional_;
public:
...
What are all the uses of an underscore in Scala?
...s taken on scala-lang.org and noticed a curious question: " Can you name all the uses of “_”? ". Can you? If yes, please do so here. Explanatory examples are appreciated.
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Grep not as a regular expression
...as grep -F. Direct invocation as fgrep is
deprecated, but is provided to allow historical applications that rely
on them to run unmodified.
For the complete reference, check:
https://www.gnu.org/savannah-checkouts/gnu/grep/manual/grep.html
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leading zeros in rails
...ds hr and min , both integers in my application. For hr field, if the user enters "1" I would like Rails to automatically pad it to "01" before saving it to the database. Also for the min field if the user enter "0" it should put in as "00".
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