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How to mkdir only if a directory does not already exist?
... run under the KornShell (ksh) on AIX. I would like to use the mkdir command to create a directory. But the directory may already exist, in which case I do not want to do anything. So I want to either test to see that the directory does not exist, or suppress the "File exists" error that mkdir t...
How do I execute a stored procedure once for each row returned by query?
...stored procedure that alters user data in a certain way. I pass it user_id and it does it's thing. I want to run a query on a table and then for each user_id I find run the stored procedure once on that user_id
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What causes java.lang.IncompatibleClassChangeError?
I'm packaging a Java library as a JAR, and it's throwing many java.lang.IncompatibleClassChangeError s when I try to invoke methods from it. These errors seem to appear at random. What kinds of problems could be causing this error?
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How do you add CSS with Javascript?
... { color: red; }', sheet.cssRules.length);
...on all but (naturally) IE8 and prior, which uses its own marginally-different wording:
sheet.addRule('strong', 'color: red;', -1);
There is a theoretical advantage in this compared to the createElement-set-innerHTML method, in that you don't have to...
C# difference between == and Equals()
...resolve to System.Object.ReferenceEquals.
Equals is just a virtual method and behaves as such, so the overridden version will be used (which, for string type compares the contents).
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How do I test if a string is empty in Objective-C?
...here is a character in it. It's just not printable following the Unicode standard.
– bmeulmeester
Jun 18 '14 at 10:40
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Converting integer to string in Python
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There is not typecast and no type coercion in Python. You have to convert your variable in an explicit way.
To convert an object in string you use the str() function. It works with any object that has a method called __str__() defined. In fact
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How can I profile C++ code running on Linux?
... a profiler, use one of the suggested ones.
However, if you're in a hurry and you can manually interrupt your program under the debugger while it's being subjectively slow, there's a simple way to find performance problems.
Just halt it several times, and each time look at the call stack. If there...
Is there a “do … until” in Python? [duplicate]
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BTW, this is called "loop-and-a-half". Python continues to support this construct because it's one of the easiest loop patterns to correctly write and understand. See cs.duke.edu/~ola/patterns/plopd/loops.html#loop-and-a-half
– B...
OO Design in Rails: Where to put stuff
I'm really enjoying Rails (even though I'm generally RESTless), and I enjoy Ruby being very OO. Still, the tendency to make huge ActiveRecord subclasses and huge controllers is quite natural (even if you do use a controller per resource). If you were to create deeper object worlds, where would you p...