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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...
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?
9 ...
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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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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fol...
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...
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...
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...
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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