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What is this crazy C++11 syntax ==> struct : bar {} foo {};?
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First, we'll take a bog-standard abstract UDT (User-Defined Type):
struct foo { virtual void f() = 0; }; // normal abstract type
foo obj;
// error: cannot declare variable 'obj' to be of abstract type 'foo'
Let's also recall that we can instantiate...
Avoiding SQL injection without parameters
...weird. The parser is capable of identifying constants in the text and can convert the SQL string to one the uses parameters artificially. It can then insert into the cache the text of this new parameterised query. Subsequent similar SQL may find its parameterised version matched in the cache. Ho...
When does static class initialization happen?
...nstantiate a class, but I access a static field, are ALL the static blocks and private static methods used to instantiate private static fields called (in order) at that instant?
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How to 'insert if not exists' in MySQL?
I started by googling, and found this article which talks about mutex tables.
10 Answers
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How to know user has clicked “X” or the “Close” button?
... get it through the sender object. Try to cast sender as a Button control, and verify perhaps for its name "CloseButton", for instance.
private void Form1_FormClosing(object sender, FormClosingEventArgs e) {
if (string.Equals((sender as Button).Name, @"CloseButton"))
// Do something pro...
How to find out which fonts are referenced and which are embedded in a PDF document
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You can extract font(s) from PDF using Online Font Converter
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PHP function overloading
... overload PHP functions. Function signatures are based only on their names and do not include argument lists, so you cannot have two functions with the same name. Class method overloading is different in PHP than in many other languages. PHP uses the same word but it describes a different pattern.
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Selecting multiple columns in a pandas dataframe
...n interface to NumPy's usual __getitem__ syntax. That said, you can easily convert a column-slicing problem into a row-slicing problem by just applying a transpose operation, df.T. Your example uses columns[1:3], which is a little misleading. The result of columns is a Series; be careful not to just...
What is the purpose of the “final” keyword in C++11 for functions?
...hat is the purpose of the final keyword in C++11 for functions? I understand it prevents function overriding by derived classes, but if this is the case, then isn't it enough to declare as non-virtual your final functions? Is there another thing I'm missing here?
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How do I break out of a loop in Scala?
...> sum+=i)
(warning--this depends on details of how the takeWhile test and the foreach are interleaved during evaluation, and probably shouldn't be used in practice!).
(1b) Use tail recursion instead of a for loop, taking advantage of how easy it is to write a new method in Scala:
var sum = 0
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