Usage of todictionary in LINQ

Previously, VAR query = xxx was used. select (C => New {C. x, C. y}); to get a two-column field in the Table. Today, an application needs to be converted to a dictionary <t, u>. It is rarely used in this way, and I forgot to write it!

 

I finally wrote it right after remembering it for a long time. I will paste it here to prepare a copy for Future Search:

Using System;
Using System. Collections. Generic;
Using System. LINQ;

Namespace Dictest
{
Class Program
{
Static   Void Main ( String [] ARGs)
{
List < Test > LST =   New List < Test > ();
For ( Int I =   0 ; I <   10 ; I ++ )
{
Lst. Add ( New Test () {ID = Guid. newguid (), num = I, name = I. tostring ()});
}

Dictionary < Guid, Int > Dic = Lst. todictionary ( New Func < Test, guid > (C => C. ID ), New Func < Test, Int > (C => C. Num )); // If you think the writing method above is too complicated, it can be simplified // Dictionary <guid, int> DIC = lst. todictionary (C => C. ID, c => C. Num );

Foreach(Guid IDInDic. Keys)
{
Console. writeline ("Key: {0} \ tvalue: {1}", ID, DIC [ID]);
}

Console. Read ();
}
}

Public   Class Test
{
Public Guid ID { Set ; Get ;}
Public   Int Num { Set ; Get ;}
Public   String Name { Set ; Get ;}
}
}

 

If you use reflector for reflection, you will find that the compiler automatically generatesCode(Some names are processed in a friendly way)

Code

[Compilergenerated]
Private   Static Func < Test, guid > Funcguid;
 
[Compilergenerated]
Private   Static Func < Test, Int > Funcint;
 
[Compilergenerated]
Private   Static   Int Mnum (test C)
{
Return C. Num;
}
 
[Compilergenerated]
Private   Static Guid mid (test C)
{
Return C. ID;
}

Private   Static   Void Main ( String [] ARGs)
{
List < Test > LST =   New List < Test > ();
For ( Int I =   0 ; I <   10 ; I ++ )
{
Test _ t =   New Test ();
_ T. ID = Guid. newguid ();
_ T. Num = I;
_ T. Name = I. tostring ();
Lst. Add (_ t );
}
Dictionary < Guid, Int > Dic = Lst. todictionary < Test, guid, Int > (Funcguid ! =   Null ) ? Funcguid: (funcguid =   New Func < Test, guid > (Program. Mid), (funcint ! =   Null ) ? Funcint: (funcint =   New Func < Test, Int > (Program. mnum )));
Foreach (Guid ID In Dic. Keys)
{
Console. writeline ( " Key: {0} \ tvalue: {1} " , ID, DIC [ID]);
}
Console. Read ();
}

SELF: http://www.cnblogs.com/yjmyzz/archive/2009/12/04/1617240.html