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Enumerators, Delegates, LINQ, Operator Overloading
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Enumerators, Delegates, LINQ, Operator Overloading
Enumerating Collections
interface IEnumerable
{
IEnumerator GetEnumerator();
}
interface IEnumerator
{
object Current {get;}
bool MoveNext();
void Reset();
}
IEnumerator<T>
Delegate is a reference to a method
They delegate processing to referenced method when called
.NET delegates List<T> : Find and Exists methods
support Func<T,TResult> and Action<T> delegates
distinct machineries for distinct tasks
-shaping
-welding-
-painting
-single controller class
Adapter
to add methods to delegates who do not follow its format
Enabling notifications by using events
event delgatetype eventname
eventname+=method
eventname-=methodname
events
Events
Querying in-memory data using query expressions
(ID,firstname,lastname,companyname)
(companyname,city,country)
Select()
- Retrieve the first names of all customers
Retrieve the first and last names of all customers
IEnumerable
JOIN
Query Operators
Employee Tree
OPERATOR OVERLOADING
features of operators:
-operate on operands
-semantic varies
-precedence
- associativity
-unary and binary
- cannot change precedence and associativity
- cannot change multiplicity of operators
- cannot invent new operator symbols
- cannot change meaning, when applied to built in types
- some operators cannot be overloaded
operator overloading
- method like syntax
-keyword operator
- should be public and static
-cannot be virtual, abstract, sealed or override
- number of parameters depend on operator multiplicity
-atleast one of the parameter should be containing type
Creating symmetric operators
compound assignment
Overloading increment and decrement operators
operator pairs
Type Conversion
Implicit
Explicit
User defined conversions
(keywords -implicit, explicit
Creating symmetric operators