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What is the difference between the | and || or operators?
I have always used || (two pipes) in OR expressions, both in C# and PHP. Occasionally I see a single pipe used: | . What is the difference between those two usages? Are there any caveats when using one over the other or are they interchangeable?
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How to check for an undefined or null variable in JavaScript?
...xistingObj.someUndefProperty. An undefined property doesn't yield an error and simply returns undefined, which, when converted to a boolean, evaluates to false. So, if you don't care about
0 and false, using if(obj.undefProp) is ok. There's a common idiom based on this fact:
value = obj.prop || de...
What is the id( ) function used for?
I read the Python 2 docs and noticed the id() function:
13 Answers
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Fast way to get image dimensions (not filesize)
I'm looking for a fast way to get the height and width of an image in pixels. It should handle at least JPG, PNG and TIFF, but the more the better. I emphasize fast because my images are quite big (up to 250 MB) and it takes soooo long to get the size with ImageMagick's identify because it obv...
Hidden features of Windows batch files
What are some of the lesser know, but important and useful features of Windows batch files?
91 Answers
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ValueError: numpy.dtype has the wrong size, try recompiling
I just installed pandas and statsmodels package on my python 2.7
When I tried "import pandas as pd", this error message comes out.
Can anyone help? Thanks!!!
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How can I get the behavior of GNU's readlink -f on a Mac?
...ption -f that follows additional links. This doesn't seem to work on Mac and possibly BSD based systems. What would the equivalent be?
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Difference between Destroy and Delete
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ActiveRecord::Persistence.delete
Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can't be persisted). Returns the frozen instance.
The row is simply removed with an SQL DELETE statement on the record's primary key, and no...
Is using 'var' to declare variables optional? [duplicate]
...use var). If you use var in the global scope, the variable is truly global and cannot be deleted.
This is, in my opinion, one of the most dangerous issues with javascript, and should be deprecated, or at least raise warnings over warnings. The reason is, it's easy to forget var and have by accident...
How to make Java honor the DNS Caching Timeout?
We use GSLB for geo-distribution and load-balancing. Each service is assigned a fixed domain name. Through some DNS magic, the domain name is resolved into an IP that's closest to the server with least load. For the load-balancing to work, the application server needs to honor the TTL from DNS respo...