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What is the difference between up-casting and down-casting with respect to class variable
What is the difference between up-casting and down-casting with respect to class variable?
10 Answers
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Safely casting long to int in Java
What's the most idiomatic way in Java to verify that a cast from long to int does not lose any information?
10 Answers
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Get the week start date and week end date from week number
...f-week value. Here is an example:
WITH TestData(SomeDate) AS (
SELECT CAST('20001225' AS DATETIME) UNION ALL
SELECT CAST('20001226' AS DATETIME) UNION ALL
SELECT CAST('20001227' AS DATETIME) UNION ALL
SELECT CAST('20001228' AS DATETIME) UNION ALL
SELECT CAST('20001229' AS DATETI...
Downcasting in Java
Upcasting is allowed in Java, however downcasting gives a compile error.
11 Answers
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How do I cast a string to integer and have 0 in case of error in the cast with PostgreSQL?
...conditionals, so you shouldn't get any non-integers hitting your ::integer cast. It also handles NULL values (they won't match the regexp).
If you want zeros instead of not selecting, then a CASE statement should work:
SELECT CASE WHEN myfield~E'^\\d+$' THEN myfield::integer ELSE 0 END FROM mytabl...
Any idea why I need to cast an integer literal to (int) here?
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The compiler tries to subtract 128 from (Integer) instead of casting -128 to Integer. Add () to fix it
Integer i3 = (Integer) -128; // doesn't compile
Integer i3 = (Integer) (-128); // compiles
According to BoltClock in the comments the cast to int works as intended, because it is ...
TypeScript: casting HTMLElement
Does anyone know how to cast in TypeScript?
13 Answers
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No Exception while type casting with a null in java
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You can cast null to any reference type without getting any exception.
The println method does not throw null pointer because it first checks whether the object is null or not. If null then it simply prints the string "null". Otherw...
How can I truncate a datetime in SQL Server?
...odern versions of Sql Server. For Sql Server 2008 and later, it's simple:
cast(getDate() As Date)
Note that the last three paragraphs near the bottom still apply, and you often need to take a step back and find a way to avoid the cast in the first place.
But there are other ways to accomplish th...
error: cannot dynamic_cast ‘b’ (of type ‘class Base*’) to type ‘c...
error: cannot dynamic_cast ‘b’ (of type ‘class Base*’) to type ‘class Derived*’ (source type is not polymorphic)在将父类型转换为子类型时,可以使用static_cast和dynamic_cast.如果使用dynamic_cast,它要求父类必须为多态的,即要求至少有一个虚函数,因此....