C #2.0 is there? : Easy to judge single branch Edition

Although C #2.0 implements the nullable data type, although it is just a small cookie, it has to be said that C # is persistently continuing its humanized features, finally, we don't need to use an object to store simple data to pass the = NULL test. On the surface, this function may not have much innovation significance, but I wonder if you have any complaints like int A = NULL in your memory like me?

For details about nullable, refer to the new features and many blogs in C #2.0.ArticleThis is not what I want to talk about. Only 2.0 provides a new operator "?? "Interesting. This operator has the following functions:

Int ? A =   1 ;
  Int ? B =   Null ;
  Int C = A; // Compile error :(
  Int C = A ??   100 ; // Right
  Int D = A + B; // Compile error yet
  Int D = A + B ??   - 1 ; // Right

See this "?? "Use, what can you think of in the first time? I first thought of it.Three-element operationOperation? :!

InCodeTo write a certain Trielement expression in the code, which is often concise and compact. However, nothing is perfect. This classic ternary operation must have two branches (well, if one branch is not a ternary operation), so sometimes I have to avoid using the if statement, write some ugly code:
1.

String Param = Request. Params [ " Param " ];
If (Param =   Null )
{
Param = defaultvalue;
}

Or

String Param = Request. Params [ " Param " ] =   Null   ? Defaultvalue: request. Params [ " Param " ];

I am disgusted with the request. Params ["key"]The same Code such as viewstate ["key"] And hasttable ["key"] is written more than once, because the literal string as the key cannot be checked by the compiler, spelling mistakes are very frustrating.

2.

Public   String Getvalue
{
Get
{
If ( This . Value =   Null )
{
Return String. Empty;
}
Else
{
Return This. Value;
}
}
}

Or

Public   String Getvalue
{
Get
{
Return This. Value= Null ? String. Empty:This. Value;
}
}

Use? : It looks good later, but it does not seem to be our hope...

In C #2.0 "?? "Operator, this type of code will become very sexy:

1. String   Params   = Reqeust. Params [ " Param " ] ?? Defaultv Alue;

2. Public   String Getvalue {Get {Return This. Value?? String. Empty ;}}

3. bool isinternal = This. session ["isinternal"] As bool? ?? False;