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Why do we need virtual functions in C++?
...eclaration and calls in a main function etc. Pointer-to-derived implicitly casts to pointer-to-base (more specialized implicitly casts to more general). Visa-versa you need an explicit cast, usually a dynamic_cast. Anything else - very prone to undefined behavior so make sure you know what you're do...
Removing leading zeroes from a field in a SQL statement
...@LeadingZeros) = 1 THEN
@LeadingZeros
ELSE
CAST(CAST(@LeadingZeros AS INT) AS VARCHAR(10))
END
SELECT @LeadingZeros
Or you can simply call
CAST(CAST(@LeadingZeros AS INT) AS VARCHAR(10))
...
Java Name Hiding: The Hard Way
...
You can cast a null to the type and then invoke the method on that (which will work, since the target object isn't involved in invocation of static methods).
((net.foo.X) null).doSomething();
This has the benefits of
being side-...
How to enumerate an enum
...reach (Suit suit in (Suit[]) Enum.GetValues(typeof(Suit)))
{
}
Note: The cast to (Suit[]) is not strictly necessary, but it does make the code 0.5 ns faster.
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Select something that has more/less than x character
...eed to use the below query.
SELECT *
FROM OPENQUERY(LINK_DB,'SELECT
CITY,
cast(STATE as varchar(40))
FROM DATABASE')
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Search for a string in Enum and return the Enum
...if the input is numeric; it just returns the parsed number, which then get cast to the enum's type. So if you want to check if some user input is a valid enum or something else, you should check for numeric content first. Since it returns a valid enum but with a value that may not exist at all in th...
Why does String.valueOf(null) throw a NullPointerException?
...n in this case, it then throws NullPointerException.
The easy "fix" is to cast the null explicitly to Object as follows:
System.out.println(String.valueOf((Object) null));
// prints "null"
Related questions
How does polymorph ambiguity distinction work?
Which overload will get selected for nul...
How is std::function implemented?
...e one generic function, specialize it with each possible functor type, and cast them to a universal function pointer type. Therefore the type information is erased.
I've cobbled up a simplified version of that. Hope it'll help
#include <iostream>
#include <memory>
template <typenam...
Convert ArrayList to String[] array [duplicate]
...ation as to what is going on here, the JVM doesn't know how to blindly downcast Object[] (the result of toArray()) to String[]. To let it know what your desired object type is, you can pass a typed array into toArray(). The typed array can be of any size (new String[1] is valid), but if it is too sm...
Is there a difference between copy initialization and direct initialization?
...nc() directly initializes the object a1. Any intermediary functional-style cast would not have any effect, because A_factory_func(another-prvalue) just "passes through" the result object of the outer prvalue to be also the result object of the inner prvalue.
A a1 = A_factory_func();
A a2(A_factor...