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Difference between is and as keyword
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is
The is operator checks if an object can be cast to a specific type.
Example:
if (someObject is StringBuilder) ...
as
The as operator attempts to cast an object to a specific type, and returns null if it fails.
Example:
StringBuilder b = someObject as StringBuil...
Java generics T vs Object
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Foo newFoo = (Foo) my.doSomething(foo);
Two advantages:
no need of casting (the compiler hides this from you)
compile time safety that works. If the Object version is used, you won't be sure that the method always returns Foo. If it returns Bar, you'll have a ClassCastException, at runtime.
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How do I fix "The expression of type List needs unchecked conversion…'?
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The warning-free approach is to create a new List<SyndEntry>, then cast each element of the sf.getEntries() result to SyndEntry before adding it to your new list. Collections.checkedList does not do this checking for you—although it would have been possible to implement it to do so.
By d...
Cast a Double Variable to Decimal
How does one cast a double to decimal which is used when doing currency development. Where does the M go?
5 Answers
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Why does an NSInteger variable have to be cast to long when used as a format argument?
...bit or 64-bit, depending on the platform, the compiler recommends
to add a cast to long generally.
Update: Since iOS 7 supports 64-bit now as well, you can get the same warning when compiling
for iOS.
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Casting a variable using a Type variable
In C# can I cast a variable of type object to a variable of type T where T is defined in a Type variable?
12 Answers
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T-SQL Cast versus Convert
What is the general guidance on when you should use CAST versus CONVERT ? Is there any performance issues related to choosing one versus the other? Is one closer to ANSI-SQL?
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Why don't Java's +=, -=, *=, /= compound assignment operators require casting?
...valent to E1 = (T)((E1) op (E2)), so that's kind of like implicit down typecasting (down from long to int). Whereas in i = i+j, we have to do it explicitly, ie, provide the (T) part in E1 = ((E1) op (E2)) Isn't it?
– bad_keypoints
Sep 22 '12 at 14:52
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Convert List to List
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The way to make this work is to iterate over the list and cast the elements. This can be done using ConvertAll:
List<A> listOfA = new List<C>().ConvertAll(x => (A)x);
You could also use Linq:
List<A> listOfA = new List<C>().Cast<A>().ToList();
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Why cast unused return values to void?
Is there any reason for casting an unused return value to void, or am I right in thinking it's a complete waste of time?
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