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Which is faster/best? SELECT * or SELECT column1, colum2, column3, etc
I've heard that SELECT * is generally bad practice to use when writing SQL commands because it is more efficient to SELECT columns you specifically need.
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Why should hash functions use a prime number modulus?
... ago, I bought a data structures book off the bargain table for $1.25. In it, the explanation for a hashing function said that it should ultimately mod by a prime number because of "the nature of math".
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SecItemAdd and SecItemCopyMatching returns error code -34018 (errSecMissingEntitlement)
... and can't be consistently reproduced. (happens maybe 30% of the time, and it's not clear to me why it happens). What makes debugging this problem very difficult is the total lack of documentation. Any idea what causes this and how to fix it? I'm using Xcode 5 and running iOS 7.0.4 on device.
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How to search all loaded scripts in Chrome Developer Tools?
In Firebug, you can search some text and it will look for it in all scripts loaded on a page. Can the same be done in Chrome Developer tools while debugging client script? I tried it, but it seems to search only in the script I have open, and not the rest that are on the page.
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Java inner class and static nested class
...StaticNestedClass();
Objects that are instances of an inner class exist within an instance of the outer class. Consider the following classes:
class OuterClass {
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class InnerClass {
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}
}
An instance of InnerClass can exist only within an instance of OuterClass and has ...
std::function vs template
...wrappers. Unfortunately, I keep hearing only bad things about these new additions. The most popular is that they are horribly slow. I tested it and they truly suck in comparison with templates.
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What's the bad magic number error?
What's the "Bad magic number" ImportError in python, and how do I fix it?
15 Answers
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Consistency of hashCode() on a Java string
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I can see that documentation as far back as Java 1.2.
While it's true that in general you shouldn't rely on a hash code implementation remaining the same, it's now documented behaviour for java.lang.String, so changing it would count as breaking existing contracts.
Wherever possible,...
Understanding Spring @Autowired usage
...llows you to skip configurations elsewhere of what to inject and just does it for you. Assuming your package is com.mycompany.movies you have to put this tag in your XML (application context file):
<context:component-scan base-package="com.mycompany.movies" />
This tag will do an auto-scann...
Simple way to repeat a String in java
... operator that allows me to repeat some String n times. I know I could write this using a for loop, but I wish to avoid for loops whenever necessary and a simple direct method should exist somewhere.
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