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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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How to cast List to List
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you can always cast any object to any type by up-casting it to Object first. in your case:
(List<Customer>)(Object)list;
you must be sure that at runtime the list contains nothing but Customer objects.
Critics say that such cast...
Integer division: How do you produce a double?
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double num = 5;
That avoids a cast. But you'll find that the cast conversions are well-defined. You don't have to guess, just check the JLS. int to double is a widening conversion. From §5.1.2:
Widening primitive conversions do not
lose informa...
How do I list all the columns in a table?
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For Oracle (PL/SQL)
SELECT column_name
FROM user_tab_cols
WHERE table_name = 'myTableName'
For MySQL
SHOW COLUMNS FROM table_name
share
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i...
Difference between DirectCast() and CType() in VB.NET
...just gotten into VB.NET. I generally use CType (and CInt, CBool, CStr) for casts because it is fewer characters and was the first way of casting which I was exposed to, but I am aware of DirectCast and TryCast as well.
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dynamic_cast and static_cast in C++
I am quite confused with the dynamic_cast keyword in C++.
10 Answers
10
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How can I combine multiple rows into a comma-delimited list in Oracle? [duplicate]
...countries values ('Andorra');
insert into countries values ('Antigua');
SELECT SUBSTR (SYS_CONNECT_BY_PATH (country_name , ','), 2) csv
FROM (SELECT country_name , ROW_NUMBER () OVER (ORDER BY country_name ) rn,
COUNT (*) OVER () cnt
FROM countries)
WHE...
How can I post an array of string to ASP.NET MVC Controller without a form?
...C and JQuery, and one of the pages is a list of items in which some can be selected. Then I would like to press a button and send a List (or something equivalent) to my controller containing the ids of the items that were selected, using JQuery's Post function.
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How is null + true a string?
...solution rules of §7.5.3 are applied to the set of candidate operators to select the best operator with respect to the argument list (x, y), and this operator becomes the result of the overload resolution process. If overload resolution fails to select a single best operator, a binding-time error o...
Ignoring time zones altogether in Rails and PostgreSQL
...n parameter before being displayed to the client.
Example (in psql):
db=# SELECT timestamptz '2012-03-05 20:00+03';
timestamptz
------------------------
2012-03-05 18:00:00+01
What happened here?
I chose an arbitrary time zone offset +3 for the input literal. To Postgres, this is just one o...