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Cast List to List in .NET 2.0
Can you cast a List<int> to List<string> somehow?
8 Answers
8
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Value of type 'T' cannot be converted to
... the compiler doesn't know that T is string.
Therefore, it doesn't let you cast. (For the same reason that you cannot cast DateTime to string)
You need to cast to object, (which any T can cast to), and from there to string (since object can be cast to string).
For example:
T newT1 = (T)(object)"so...
What is SuppressWarnings (“unchecked”) in Java?
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In some cases, you can avoid it by using YourClazz.class.cast(). Works for single generic element containers but not for collections.
– akarnokd
Jul 15 '09 at 7:30
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MySQL selecting yesterday's date
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You can get yesterday's date by using the expression CAST(NOW() - INTERVAL 1 DAY AS DATE). So something like this might work:
SELECT * FROM your_table
WHERE DateVisited >= UNIX_TIMESTAMP(CAST(NOW() - INTERVAL 1 DAY AS DATE))
AND DateVisited <= UNIX_TIMESTAMP(CAST(NOW...
How do I convert a string to a number in PHP?
...mstances. For situations where you do want to explicitly convert the type, cast it:
$num = "3.14";
$int = (int)$num;
$float = (float)$num;
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Does it make sense to use “as” instead of a cast even if there is no null check? [closed]
.... That sounds like trying to micro-optimize to me. You should use a normal cast when you are sure of the type. Besides generating a more sensible exception, it also fails fast. If you're wrong about your assumption about the type, your program will fail immediately and you'll be able to see the caus...
C++ equivalent of java's instanceof
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Try using:
if(NewType* v = dynamic_cast<NewType*>(old)) {
// old was safely casted to NewType
v->doSomething();
}
This requires your compiler to have rtti support enabled.
EDIT:
I've had some good comments on this answer!
Every time you need...
How does std::forward work? [duplicate]
...does according to the standard:
§20.2.3 [forward] p2
Returns: static_cast<T&&>(t)
(Where T is the explicitly specified template parameter and t is the passed argument.)
Now remember the reference collapsing rules:
TR R
T& & -> T& // lvalue reference to c...
How can I group by date time column without taking time into consideration
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Cast/Convert the values to a Date type for your group by.
GROUP BY CAST(myDateTime AS DATE)
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Casting to string in JavaScript
I found three ways to cast a variable to String in JavaScript.
I searched for those three options in the jQuery source code, and they are all in use .
I would like to know if there are any differences between them:
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