The document summarizes new features in .NET 3.5 including implicitly typed local variables, automatic properties, object and collection initializers, extension methods, lambda expressions, query syntax, and anonymous types. Key features are variables that infer type from initialization value, simplified property declarations, initializing objects and collections in a single statement, extending types without inheritance, lambda functions, LINQ query syntax, and anonymous class types without names.

1. .Net 3.5
-Prabhakaran

2. .Net 3.5 Framework

3. What is new in 3.5 C#?
 Implicitly Typed Local Variables
 Automatic Properties
 Object Initializer
 Collection Initializers
 Extension Methods
 Lambda Expressions
 Query Syntax
 Anonymous Types
 Expression Trees

4. Implicitly Typed Local Variables
Examples:
var i = 5;
var s = "Hello";
var d = 1.0;
var numbers = new int[] {1, 2, 3};
var orders = new Dictionary<int,Order>();
Are equivalent to:
int i = 5;
string s = "Hello";
double d = 1.0;
int[] numbers = new int[] {1, 2, 3};
Dictionary<int,Order> orders = new
Dictionary<int,Order>();
Errors:
var x; // Error, no initializer to infer type from
var y = {1, 2, 3}; // Error, collection initializer not
permitted
var z = null; // Error, null type not permitted

5. Automatic Properties
 public class Person {
private string _firstName;
private string _lastName;
private int _age;
public string FirstName {
get {
return _firstName;
}
set {
_firstName = value;
}
}
public string LastName {
get {
return _lastName;
}
set {
_lastName = value;
}
}
public int Age {
get {
return _age;
}
set {
_age = value; } } }

6.  For example, using automatic properties I can now re-write the code
above to just be:
 public class Person {
public string FirstName {
get; set;
}
public string LastName {
get; set;
}
public int Age {
get; set;
}
}
 Or If I want to be really terse, I can collapse the whitespace even further
like so:
 public class Person {
public string FirstName { get; set; }
public string LastName { get; set; }
public int Age { get; set; }
}

7. Object Initializer
Person person = new Person();
person.FirstName = "Scott";
person.LastName = "Guthrie";
person.Age = 32;
3.5
Person person = new Person { FirstName="Scott", Last
Name="Guthrie", Age=32 };
Person person = new Person {
FirstName = "Scott",
LastName = "Guthrie"
Age = 32,
Address = new Address {
Street = "One Microsoft Way",
City = "Redmond",
State = "WA",
Zip = 98052
}
};

8. Collection Initializers
List<Person> people = new List<Person>();
people.Add( new Person { FirstName = "Scott", LastName = "Guthrie", A
ge = 32 } );
people.Add( new Person { FirstName = "Bill", LastName = "Gates", Age
= 50 } );
people.Add( new Person { FirstName = "Susanne", LastName = "Guthrie
", Age = 32 } );
3.5
List<Person> people = new List<Person> {
new Person { FirstName = "Scott", LastName = "Guthrie", Age = 32 },
new Person { FirstName = "Bill", LastName = "Gates", Age = 50 },
new Person { FirstName = "Susanne", LastName = "Guthrie", Age = 3
2}
};

9. Extension Methods
Extension methods allow developers to add new methods to the public contract of an
existing CLR type, without having to sub-class it or recompile the original type.
Example:
string email = Request.QueryString["email"];
if ( EmailValidator.IsValid(email) ) {
}
3.5
string email = Request.QueryString["email"];
if ( email.IsValidEmailAddress() ) {
}
public static class ScottGuExtensions
{
public static bool IsValidEmailAddress(this string s)
{
Regex regex = new Regex(@"^[w-.]+@([w-]+.)+[w-]{2,4}$");
return regex.IsMatch(s);
}
}

11. Lambda Expressions

12. Query Syntax
 Query syntax is a convenient declarative shorthand for expressing queries
using the standard LINQ query operators.

13. Anonymous Types