Презентация на тему Interfaces. C# Collections

listOfInterfaces opt
{
//declaration of interface members
}
Interface Includes

only declaration of method, properties, events, indexers
Interface can't contain constants, fields, operators, instance constructors, destructors, or types.
Interface members are automatically public, and they can't include any access modifiers.
Interface members can't be static.

An interface contains definitions for a group of related functionalities that a class or a struct can implement

float this [int index] { get; set; }

string

Name { get; set; }

event MouseEventHandler Mouse;
}

(int side);
void Block();
}
class Soldier : IFighter
{
public void

Punch(int side)
{
Move(arms[side], Forward);
}
public void Kick (int side)
{
Move(legs[side], Forward);
}
public void Block()
{
Move(arms[Left ], Up);
Move(arms[Right], Up);
}
public void Move(Arm a,Direction d)
{
…
}
public void Move(Leg l,Direction d)
{
…
}
}

IFighter f = new Soldier();
f.Punch(Left);
f.Kick(Right);
f.Block();

IFighter s= new Dragon();
s.Punch(Left);
s.Kick(Right);
s.Block();
...

class Dragon : IFighter
{
public void Punch(int side)
{
Move(tail, side);
}
public void Kick (int side)
{
Move(legs[side], Forward);
}
public void Block()
{
Move(legs[Left ], Up);
Move(tail, Up);
}
}

must implement all its members.
By using interfaces, we may

include behavior from multiple sources in a class.
It is important in C# because the language doesn't support multiple inheritance of classes.
We must use an interface for simulating inheritance for structs, because they can't actually inherit from another struct or class.

Interface Implementation

string Introduce();
}
interface IFighter
{
void Punch(int side);
void Kick (int

side);
void Block();
}

Interface Implementation

allows foreach-loops on collections. It is often used in

LINQ.

IDisposable:
Provides a mechanism for releasing unmanaged resources

ICollection:
Defines methods to manipulate generic collections.

return salary-other.salary;
}
...
}
public static void Main()
{
Doctor [] doctors= new

Doctor [5];
//… input doctors

Array.Sort(doctors);

classes Bird (with fields: name and canFly) and Plane

(with fields: mark and highFly) , which implement interface IFlyable.
Create List of IFlyable objects and add some Birds and Planes to it. Call Fly() method for every item from the list of it.

storage and retrieval.
There are two distinct collection types in

C#:
The standard collections from the System.Collections namespace
The generic collections from System.Collections.Generic.
 Generic collections are more flexible and safe, and are the preferred way to work with data. 

ArrayList
Dictionary

HashTable
SortedList, SortedDictionary SortedList
Stack Stack
Queue Queue
LinkedList О(1) -

IList IList
IDictionary IDictionary
ICollection ICollection
IEnumerator IEnumerator
IEnumerable IEnumerable
IComparer ІComparer
IComparable IComparable

with some functionality over and above that of the

standard Array.
Unlike arrays, an ArrayList can hold data of multiple data types.
We can dynamically resize it by simply adding and removing elements.

using System.Collections;

class Department
{
ArrayList employees = new ArrayList();
...
}

create ArrayList

Add (object value) // at the end
void

Insert(int index, object value) ...

void Remove (object value) ...
void RemoveAt(int index) ...
void Clear () ...

bool Contains(object value) ...
int IndexOf (object value) ...

object this[int index] { get... set.. }

int Capacity { get... set... }
void TrimToSize() //minimize memory
...
}

control of memory
in underlying array

add new elements

remove

containment testing

read/write existing element

da.Add(55);
da.Add(new Empty());

da.Remove(55);

foreach(object el in da)
{

Console.WriteLine(el);
}

class Empty {}

using System.Collections;

can be accessed by index.
It can be found under

System.Collections.Generic namespace

List();
langs.Add("Java");
langs.Add("C#");
langs.Add("C++");
langs.Add("Javascript");

Console.WriteLine(langs.Contains("C#"));
Console.WriteLine(langs[1]);

langs.Remove("C#");
Console.WriteLine(langs.Contains("C#"));

langs.Insert(2, "Haskell");
langs.Sort();
foreach(string lang in langs)
{ Console.WriteLine(lang); }
}

using System.Collections.Generic;

foreach (int value in values)
{

Console.WriteLine(value);
}
}

static void Main()
{
int[] values = { 1, 2, 3 };
List values2 = new List() { 1, 2, 3 };

// Pass to a method that receives IEnumerable.
Display(values);
Display(values2);
}

collection of unique keys and a collection of values
Each

key is associated with one value.
Retrieving and adding values is very fast.

country names:




Retrieve values by their keys and print the

number of items: 



Print both keys and values of the dictionary:

Dictionary domains = new Dictionary();
domains.Add("de", "Germany");
domains.Add("sk", "Slovakia");
domains.Add("us", "United States");

Console.WriteLine(domains["sk"]);
Console.WriteLine(domains["de"]);
Console.WriteLine("Dictionary has {0} items", domains.Count);

foreach(KeyValuePair kvp in domains)
{
Console.WriteLine("Key = {0}, Value = {1}", kvp.Key, kvp.Value);
}

The first element added to the queue will be

the first one to be removed.
Queues may be used to process messages as they appear or serve customers as they come.
Methods:
Clear(); removes all elements from the Queue.
Contains(object obj); determines whether an element is in the Queue.
Dequeue(); removes and returns the object at the beginning of the Queue.
Enqueue(object obj); adds an object to the end of the Queue.
ToArray(); Copies the Queue to a new array.

msgs.Enqueue("Message 1");
msgs.Enqueue("Message 2");

msgs.Enqueue("Message 3");


Console.WriteLine(msgs.Dequeue());
Console.WriteLine(msgs.Peek());
Console.WriteLine(msgs.Peek());

Console.WriteLine();

foreach(string msg in msgs)
{
Console.WriteLine(msg);
}

element added to the queue will be the first

one to be removed.
The C language uses a stack to store local data in a function. The stack is also used when implementing calculators.

stc.Push(1);
stc.Push(4);
stc.Push(3);

stc.Push(6);

Console.WriteLine(stc.Pop());
Console.WriteLine(stc.Peek());
Console.WriteLine(stc.Peek());

Console.WriteLine();

foreach(int item in stc)
{
Console.WriteLine(item);
}

fill it from Console.
1) Find and print all positions

of element -10 in the collection
2) Remove from collection elements, which are greater then 20.
Print collection
3) Insert elements 1,-3,-4 in positions 2, 8, 5. Print collection
4) Sort and print collection
Use next Collections for this tasks: List and ArrayList

methods Create() and Destroy()
Create two classes

Programmer (with field language) and Builder (with field tool), which implement this interface.
Create List of IDeveloper and add some Programmers and Builders to it. Call Create() and Destroy() methods, property Tool for all of it

2. Create Console Application project in VS. In the Main() method declare Dictionary. Add to Dictionary from Console seven pairs (ID, Name) of some persons. Ask user to enter ID, then find and write corresponding Name from your Dictionary. If you can't find this ID - say about it to user.