大约有 40,000 项符合查询结果（耗时：0.0470秒） [XML]
FirstOrDefault: Default value other than null
...FirstOrDefault().IfDefaultGiveMe(otherDefaultValue);
Again, this can't really tell if there was anything in your sequence, or if the first value was the default.
If you care about this, you could do something like
static class ExtensionsThatWillAppearOnIEnumerables
{
public static T FirstOr&...
Deep cloning objects
...ts too complex.
And with the use of extension methods (also from the originally referenced source):
In case of you prefer to use the new extension methods of C# 3.0, change the method to have the following signature:
public static T Clone<T>(this T source)
{
//...
}
Now the method call sim...
UCenter实现各系统通信的原理 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...原理
1、用户登录bbs，通过logging.php文件中，使用函数uc_user_login验证，如果验证成功，将调用函数uc_user_synlogin（位于uc_client下的client.php文件中）， 在这个函数中调用 uc_api_post('user', 'synlogin', array('uid'=>$uid));之后向UC_API.'/index.php'...
LINQ, Where() vs FindAll()
Can someone explain how the LINQ functions Where(..) and FindAll(..) differ? They both seem to do the same thing...
4 Answe...
Convert a string to an enum in C#
... true);
}
StatusEnum MyStatus = "Active".ToEnum<StatusEnum>();
Finally, you may want to have a default enum to use if the string cannot be parsed:
public static T ToEnum<T>(this string value, T defaultValue)
{
if (string.IsNullOrEmpty(value))
{
return defaultValue;
...
Strange, unexpected behavior (disappearing/changing values) when using Hash default value, e.g. Hash
...ere’s a hint:
h[42] #=> ["a", "b"]
The array returned by each [] call is just the default value, which we’ve been mutating all this time so now contains our new values. Since << doesn’t assign to the hash (there can never be assignment in Ruby without an = present†), we’ve nev...
How do I obtain a Query Execution Plan in SQL Server?
...an execution plan, which one to use will depend on your circumstances. Usually you can use SQL Server Management Studio to get a plan, however if for some reason you can't run your query in SQL Server Management Studio then you might find it helpful to be able to obtain a plan via SQL Server Profil...
MongoDB: Combine data from multiple collections into one..how?
..., reduce;
db.users_comments.remove();
// setup sample data - wouldn't actually use this in production
db.users.remove();
db.comments.remove();
db.users.save({firstName:"Rich",lastName:"S",gender:"M",country:"CA",age:"18"});
db.users.save({firstName:"Rob",lastName:"M",gender:"M",country:"US",age:"25...
Passing parameters to addTarget:action:forControlEvents
...wsDetails: method here. You just create a selector to make button able to call it when certain action occurs (touch up in your case). Controls can use 3 types of selectors to respond to actions, all of them have predefined meaning of their parameters:
with no parameters
action:@selector(switchToN...
What is a predicate in c#? [duplicate]
...cate<T> is a functional construct providing a convenient way of basically testing if something is true of a given T object.
For example suppose I have a class:
class Person {
public string Name { get; set; }
public int Age { get; set; }
}
Now let's say I have a List<Person> p...