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Return a “NULL” object if search result not found
I'm pretty new to C++ so I tend to design with a lot of Java-isms while I'm learning. Anyway, in Java, if I had class with a 'search' method that would return an object T from a Collection< T > that matched a specific parameter, I would return that object and if the object was not found in...
Why does .NET foreach loop throw NullRefException when collection is null?
So I frequently run into this situation... where Do.Something(...) returns a null collection, like so:
11 Answers
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A std::map that keep track of the order of insertion?
I currently have a std::map<std::string,int> that stores an integer value to an unique string identifier, and I do look up with the string. It does mostly what I want, except for that it does not keep track of the insertion order. So when I iterate the the map to print out the values, they a...
Convert base class to derived class [duplicate]
Is it possible in C# to explicitly convert a base class object to one of it's derived classes? Currently thinking I have to create a constructor for my derived classes that accept a base class object as a parameter and copy over the property values. I don't really like this idea, so I'd like to avoi...
Secure hash and salt for PHP passwords
It is currently said that MD5 is partially unsafe. Taking this into consideration, I'd like to know which mechanism to use for password protection.
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Is there an alternative to bastard injection? (AKA poor man's injection via default constructor)
I most commonly am tempted to use "bastard injection" in a few cases. When I have a "proper" dependency-injection constructor:
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What is a difference between
What is the difference between <? super E> and <? extends E> ?
9 Answers
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Efficiency of purely functional programming
Does anyone know what is the worst possible asymptotic slowdown that can happen when programming purely functionally as opposed to imperatively (i.e. allowing side-effects)?
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How to keep one variable constant with other one changing with row in excel
Lets say I have one cell A1, which I want to keep constant in a calculation. For example, I want to calculate a value like this:
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Add column with constant value to pandas dataframe [duplicate]
Given a DataFrame:
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