大约有 30,000 项符合查询结果（耗时：0.0424秒） [XML]
NSUserDefaults - How to tell if a key exists
...l returning nil if the key doesn't exist.
func integerOptional(forKey: String) -> Int? {
return self.object(forKey: forKey) as? Int
}
/// Convenience method to wrap the built-in .double(forKey:) method in an optional returning nil if the key doesn't exist.
func doubleOptio...
How to add http:// if it doesn't exist in the URL?
...
Scan the string for ://, if it does not have it, prepend http:// to the string.., everything else just use the string as is.
This will work unless you have rubbish input string.
...
INSERT INTO…SELECT for all MySQL columns
...coln
FROM this_table
WHERE entry_date < '2011-01-01 00:00:00';
If the id columns is an auto-increment column and you already have some data in both tables then in some cases you may want to omit the id from the column list and generate new ids instead to avoid insert an id that already exists i...
Using the HTML5 “required” attribute for a group of checkboxes?
...
Unfortunately HTML5 does not provide an out-of-the-box way to do that.
However, using jQuery, you can easily control if a checkbox group has at least one checked element.
Consider the following DOM snippet:
<div class="checkbox-group required">
...
What's the best name for a non-mutating “add” method on an immutable collection?
...you always have to build from the empty list.
var list = ImmutableList<string>.Empty.And("Hello")
.And("Immutable")
.And("Word");
share
...
How to use Greek symbols in ggplot2?
...like adding '*' to the ticks)
Just use unicode characters within the text string.
seems to work well for all options I can think of.
Edit: previously it did not work in facet labels. This has apparently been fixed at some point.
library(ggplot2)
ggplot(mtcars,
aes(mpg, disp, color=factor...
Convert a series of parent-child relationships into a hierarchical tree?
...];
}
}
unset($flat);
That's all for getting the hierarchy into a multidimensional array:
Array
(
[children] => Array
(
[0] => Array
(
[children] => Array
(
[0] => Array
...
SignalR: Why choose Hub vs. Persistent Connection?
...ver side in the OnReceived method. You'd also have to deserialize the data string there instead of receiving the strongly typed objects as you do with hub methods.
There aren't many reasons to choose PersistentConnection over Hubs. One reason I'm aware of is that it is possible to send preserialize...
How do you UrlEncode without using System.Web?
...
System.Uri.EscapeUriString() can be problematic with certain characters, for me it was a number / pound '#' sign in the string.
If that is an issue for you, try:
System.Uri.EscapeDataString() //Works excellent with individual values
Here is ...
Add a column to a table, if it does not already exist
...bjects.
IF NOT EXISTS (
SELECT *
FROM sys.columns
WHERE object_id = OBJECT_ID(N'[dbo].[Person]')
AND name = 'ColumnName'
)
share
|
improve this answer
|
...