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Regular expression for a hexadecimal number?
...fA-F]+
Matches expression starting with a 0, following by either a lower or uppercase x, followed by one or more characters in the ranges 0-9, or a-f, or A-F
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In HTML5, should the main navigation be inside or outside the element?
In HTML5, I know that <nav> can be used either inside or outside the page's masthead <header> element. For websites having both secondary and main navigation, it seems common to include the secondary navigation as a <nav> element inside the masthead <header> element ...
How are virtual functions and vtable implemented?
...ver a program has a virtual function declared, a v - table is constructed for the class. The v-table consists of addresses to the virtual functions for classes that contain one or more virtual functions. The object of the class containing the virtual function contains a virtual pointer that points t...
How to check if a variable is set in Bash?
... does not require quotes (since it either expands to x (which contains no word breaks so it needs no quotes), or to nothing (which results in [ -z ], which conveniently evaluates to the same value (true) that [ -z "" ] does as well)).
However, while quotes can be safely omitted, and it was not imm...
Conditions for automatic generation of default/copy/move ctor and copy/move assignment operator?
I want to refresh my memory on the conditions under which a compiler typically auto generates a default constructor, copy constructor and assignment operator.
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Boolean operators && and ||
According to the R language definition , the difference between & and && (correspondingly | and || ) is that the former is vectorized while the latter is not.
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How to determine if binary tree is balanced?
...st at a hospital. Trying to move to do some actual programming now. I'm working on binary trees now, and I was wondering what would be the best way to determine if the tree is height-balanced.
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Formula to determine brightness of RGB color
I'm looking for some kind of formula or algorithm to determine the brightness of a color given the RGB values. I know it can't be as simple as adding the RGB values together and having higher sums be brighter, but I'm kind of at a loss as to where to start.
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Why can't I use float value as a template parameter?
When I try to use float as a template parameter, the compiler cries for this code, while int works fine.
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How to avoid isset() and empty()
...undefined" and "undefined offset" messages when running on the E_NOTICE error level, because the existence of variables is not explicitly checked using isset() and consorts.
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