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Adding :default => true to boolean in existing Rails column
I've seen a few questions (namely this one ) here on SO about adding a default boolean value to an existing column. So I tried the change_column suggestion but I mustn't be doing it right.
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Replacing some characters in a string with another character
I have a string like AxxBCyyyDEFzzLMN and I want to replace all the occurrences of x , y , and z with _ .
5 Answers
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Throwing cats out of windows
Imagine you're in a tall building with a cat. The cat can survive a fall out of a low story window, but will die if thrown from a high floor. How can you figure out the longest drop that the cat can survive, using the least number of attempts?
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Why does sed not replace all occurrences?
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You should add the g modifier so that sed performs a global substitution of the contents of the pattern buffer:
echo dog dog dos | sed -e 's:dog:log:g'
For a fantastic documentation on sed, check http://www.grymoire.com/Unix/Sed.html. This g...
Upgrade Node.js to the latest version on Mac OS
Currently I am using Node.js v0.6.16 on Mac OS X 10.7.4. Now I want to upgrade it to the latest Node.js v0.8.1. But after downloading and installing the latest package file from nodejs.org, I found that system is still using v0.6.16 instead of v0.8.1 when I typed "node -v" in a terminal. Is there an...
How to PUT a json object with an array using curl
...f data to enter into database. The user interface to enter the data isn't good for bulk entry, so I'm trying to formulate a command line equivalent. When I examine the network request of the UI in chrome, I see a PUT request of a json object. When I try to replicate the request
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Is optimisation level -O3 dangerous in g++?
I have heard from various sources (though mostly from a colleague of mine), that compiling with an optimisation level of -O3 in g++ is somehow 'dangerous', and should be avoided in general unless proven to be necessary.
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ld cannot find an existing library
I am attempting to link an application with g++ on this Debian lenny system. ld is complaining it cannot find specified libraries. The specific example here is ImageMagick, but I am having similar problems with a few other libraries too.
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How to print like printf in Python3?
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print ("Hi")
In both versions, % is an operator which requires a string on the left-hand side and a value or a tuple of values or a mapping object (like dict) on the right-hand side.
So, your line ought to look like this:
print("a=%d,b=%d" % (f(x,n),g(x,n)))
Also, the recommendation for Pyt...
How do I create a transparent Activity on Android?
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Add the following style in your res/values/styles.xml file (if you don’t have one, create it.) Here’s a complete file:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<style name="Theme.Transparent" parent="android:T...