大约有 42,000 项符合查询结果（耗时：0.0439秒） [XML]
How to use performSelector:withObject:afterDelay: with primitive types in Cocoa?
...trick if it is a BOOL parameter.
Pass nil for NO and self for YES. nil is cast to the BOOL value of NO. self is cast to the BOOL value of YES.
This approach breaks down if it is anything other than a BOOL parameter.
Assuming self is a UIView.
//nil will be cast to NO when the selector is perform...
How to prevent form resubmission when page is refreshed (F5 / CTRL+R)
...problem is that after the user submits the text, they can refresh the page and the data gets submitted again without filling the form again. I could redirect the user to another page after the text is submitted, but I want users to stay on the same page.
...
Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '=
...s not suffer of performance issues.
Using Option 1 and 2, aka the COLLATE cast approach, can lead to potential bottleneck, cause any index defined on the column will not be used causing a full scan.
Even though I did not try out Option 3, my hunch is that it will suffer the same consequences of op...
Passing a single item as IEnumerable
...f you pass in a list or an array, then an unscrupulous piece of code could cast it and change the contents, leading to odd behaviour in some situations. You could use a read-only collection, but that's likely to involve even more wrapping. I think your solution is as neat as it gets.
...
Is there a Python equivalent to Ruby's string interpolation?
...
@Caste see here: docs.python.org/library/stdtypes.html#string-formatting and post a follow up comment if you need any more details
– mikej
Dec 15 '10 at 13:59
...
Cannot create an array of LinkedLists in Java…?
...
For some reason you have to cast the type and make the declaration like this:
myMatrix = (LinkedList<IntegerNode>[]) new LinkedList<?>[numRows];
share
|
...
Running multiple commands with xargs
In the example above, xargs takes echo % as the command argument. But in some cases, I need multiple commands to process the argument instead of one. For example:
...
How to do ToString for a possibly null object?
...
C# 6.0 Edit:
With C# 6.0 we can now have a succinct, cast-free version of the orignal method:
string s = myObj?.ToString() ?? "";
Or even using interpolation:
string s = $"{myObj}";
Original Answer:
string s = (myObj ?? String.Empty).ToString();
or
string s = (myObjc ?? "")....
What is a raw type and why shouldn't we use it?
... String name = (String) o;
System.out.println(name);
} // throws ClassCastException!
// java.lang.Boolean cannot be cast to java.lang.String
Now we run into trouble at run-time, because names contains something that isn't an instanceof String.
Presumably, if you want names to contain only...
What are POD types in C++?
...en pointers to vtables, offsets that get applied to the address when it is cast to other types (at least if the target's POD too), constructors, or destructors. Roughly speaking, a type is a POD when the only things in it are built-in types and combinations of them. The result is something that "act...