2) for C# Only
Compiling .NET to Machine Code
How to Write High-Performance C# Code | .NET Developer’s Journal (2004)
Performance (C#) (MSDN)
Effective C# – Part I 
How to write friendlier code for the Garbage Collector and to gain performance boost
An in depth look at for loops  and For loop follow up (Disagreeing with Richter?!)
3) example
High-Performance Timer in C# / General / C#   [another]

c:\app\20090331\
c:\app\20090430\
c:\app\20090531\
c:\app\20090630\
c:\app\20090731\
c:\app\20090831\

I want to the directories between 20090531 and 20090731, How can I do it by Linq?
the answer is
var query = directories .Where(x => { return (String.Compare(x, @”c:\app\20090531″) > 0 && String.Compare(x, @”c:\app\20090731″) < 0) ;});

Points to understand Linq:  (from Joseph Rattz’s book)
1)  linq, a query,  returnes set of objects is called a sequence.  Most linq sequences are of type IEnumerable<T>
2)  a lambda expression in C# with format:   
         a) (param1, param2, …paramN) => expr
         b)  (param1, param2, …paramN) =>   {   statement1; statement2; … statementN; return(lambda_expression_return_type); }
       e.g:    x => x.Length > 0   could be read as   “input x returns x.Length > 0.”

Linq Wiki
get data from Excel by linq

4 microsoft 101 samples

5: 7 tricks to simplify your programs with LINQ | Igor Ostrovsky Blogging

4)  XML
ds as new dataset
ds.tables.add(yourtable)
ds.writexml(“yourfile”)

dependency properties add value on top of plain .NET properties:
. Change notification  — Whenever the value of a dependency property changes, WPF can automatically
                                                 trigger a number of actions depending on the property’s metadata, see trigger
. Property value inheritance  — flowing of property values down the element tree.
. Support for multiple providers  — a five-step process  (see p57)

For example, the data binding system in WPF is rooted in the FrameworkElement.DataContext dependency property.  The value of that property is inherited by all descendant elements. For more see Josh’s blog

Business objects – without  dependency properties  (see the details )  
For a business object being bound, there are certain requirements for automatic change notification. There are three approaches you can take:

• Implement dependency properties in your business object. 
• Raise an event named <Property Name>Changed. This event must match the property name, and the class must raise the event.
• Implement the INotifyPropertyChanged in the System.ComponentModel namespace. This interface defines a PropertyChanged event. The business object must fire this event every time any property value changes.

from
SpeechSynthesizer ttsSynth = new SpeechSynthesizer();
 ttsSynth.SelectVoice(“Microsoft Anna”);
//ttsSynth.Volume =  //ttsSynth.Rate 
 ttsSynth.Speak(“Greetings, my name is ” + ttsSynth.Voice.Name);

A delegate is thus equivalent to a type-safe function pointer or a callback