最全數據結構詳述: List VS IEnumerable VS IQueryable VS ICo

時間 2020-01-02

標籤數據結構詳述 list ienumerable iqueryable ico 简体版

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本文對經常使用的數據結構詳述：Array, ArrayList，List，IList，ICollection, Stack, Queue, HashTable, Dictionary, IQueryable, IEnumerable。 sql

Collection（集合）

Collection是數據記錄集合，

編寫代碼過程當中，經常須要合適的容器保存臨時數據，方便修改和查找，如何選取合適的數據容器，關鍵在於將執行的數據操做以及數據記錄是否大量。數據庫

Array（數組）

特徵數組

1. 固定大小，數組的大小是初始化時決定沒法修改的數值。服務器

2. 強類型，存儲數據元素類型必須在初始化時指定，所以在運行時，不須要耗費額外的時間來定義數組類型，可以大大提高運行效率。數據結構

3. 可以使用Foreach關鍵字實現數組迭代和查找。 app

由於數組大小是固定的，且是強類型數據結構，所以在運行時只佔用不多的內存，運行時效率很高。 dom

 1: //It is obvious that strArray is

 2:  //1. string --> Strongly Type

 3:  //2. Sized=10 --> Fixed Size

4:

 5:  string[] strArray = new string[10];

6:

 7:  for (int i = 0; i < 10; i++)

 8:  {

 9:  if (strArray[i]==null)

 10:  {

 11:  strArray[i] = (i+1).ToString();

 12:  }

 13:  }

14:

 15:  this.ListBoxArray.DataSource = null;

 16:  this.ListBoxArray.Items.Clear();

17:

 18:  this.ListBoxArray.DataSource = strArray;

 19:  this.ListBoxArray.DataBind();

ArrayList

1. ArrayList 沒有固定的長度，容量可動態增長，可應用於開發人員沒法肯定數組元素個數等場景，固然這種狀況下，在定義結構體的時候會很是耗時。函數

2. ArrayList 不是強類型，ArrayList中不一樣元素類型能夠不相同，而且須要在運行時根據實際的輸入來肯定元素類型。所以在運行時消耗內存較多。性能

3. 可以使用Froeach 關鍵字操做ArrayList。大數據

 1: public class Product

 2:  {

 3:  public Product()

 4:  {

5:

 6:  }

 7:  public Product(string Code, string Name)

 8:  {

 9:  _Code = Code;

 10:  _Name = Name;

 11:  }

12:

 13:  public string _Code {get; set;}

 14:  public string _Name { get; set; }

 15:  }

ArrayList支持String,int,以及十進制小數類型。

 1: //It is NOT obvious that strArrayList is 1. string? int? object? decimal? --> NOT Strongly Type

 2:  // 2. Sized=10? 20? 100? -->NOT Fixed Size

 3:  // Namespace: System.Collections

4:

 5:  System.Collections.ArrayList strArrayList = new System.Collections.ArrayList();

 6:  //System.Linq.IQueryable type of data is not specific runtime defered support

 7:  strArrayList.Add("Mahsa"); // "Mahsa": is string

 8:  strArrayList.Add(1); // 1 : is integer

 9:  strArrayList.Add(0.89); // 0.89: is decimal

10:

 11:  this.ListBoxArrayList.DataSource = null;

 12:  this.ListBoxArrayList.Items.Clear();

 13:  this.ListBoxArrayList.DataSource = strArrayList;

 14:  this.ListBoxArrayList.DataBind();

15:

 16:  System.Text.StringBuilder str= new System.Text.StringBuilder();

17:

 18:  foreach (var item in strArrayList)

 19:  {

 20:  str.Append(" , "+item);

 21:  }

 22:  this.lblArrayList.Text = str.ToString();

23:

 24:  //Below is old way to fill obj from product , in Arraylist you need to create more than one instance

 25: // Product objProduct = new Product();

 26: // objProduct.Code = "1001";

 27: // objProduct.Name = "Chair";

28:

 29:  //It is NOT obvious that strArrayList is

 30:  //1. string? int? object? decimal? OR OBJECT?? --> NOT Strongly Type

 31:  //2. Sized=10? 20? 100? -->NOT Fixed Size

 32:  // Namespace: System.Collections

33:

 34:  System.Collections.ArrayList objArrayList = new System.Collections.ArrayList();

35:

 36:  objArrayList.Add(new Product("1001", "Chair"));

 37:  objArrayList.Add(new Product("1002", "Sofa"));

 38:  objArrayList.Add(new Product("1003", "Carpet"));

39:

 40:  this.DropDownListArrayListObject.DataSource = null;

 41:  this.DropDownListArrayListObject.Items.Clear();

 42:  this.DropDownListArrayListObject.DataSource = objArrayList;

43:

 44:  //* Finding among Object of Array List is difficult , you have to find your specific item by index

 45:  Product objTemp = (Product)objArrayList[0];

 46:  objArrayList.Remove(objTemp);

 47:  //*

 48:  this.DropDownListArrayListObject.DataTextField = "_Name";

 49:  this.DropDownListArrayListObject.DataValueField = "_Code";

 50:  this.DropDownListArrayListObject.DataBind();

 51:  this.GridViewArrayListObject.DataSource = objArrayList;

 52:  this.GridViewArrayListObject.DataBind();

HashTable（哈希表）

HashTable是一種定義關鍵字的數據結構體，使用哈希表查找數據很是方便，哈希表既不是強類型也不固定大小限制。

 1: //It is NOT obvious that strArrayList is

 2:  //1. string? int? object? decimal? OR OBJECT?? --> NOT Strongly Type

 3:  //2. Sized=10? 20? 100? -->NOT Fixed Size

 4:  // Namespace: System.Collections

 5:  //Hashtable solve the problem in Arraylist when we are looking for specific item

 6:  //Hashtable dedicate a key for each item, then finding item is easier and faster

7:

 8:  System.Collections.Hashtable objHashTable = new System.Collections.Hashtable();

9:

 10:  objHashTable.Add("1001","Chair");

 11:  objHashTable.Add("1002", "Sofa");

 12:  objHashTable.Add("1003", "Carpet");

13:

14:

 15:  this.DropDownListHashTable.DataSource = null;

 16:  this.DropDownListHashTable.Items.Clear();

 17:  this.DropDownListHashTable.DataSource = objHashTable;

 18:  //* finding item is easier you just need to point to it by call its key

 19:  objHashTable.Remove("1002");

 20:  //*

 21:  this.DropDownListHashTable.DataTextField = "Value";

 22:  this.DropDownListHashTable.DataValueField = "Key";

 23:  this.DropDownListHashTable.DataBind();

Stack

棧是最典型的數據結構，棧具備優先級劃分的數據結構，棧爲每一個內容項定義優先級，表示每一個Item入棧和出棧的優先順序。所以操做棧中的數據，須要先將數據push 到棧的頂部，須要刪除元素必須變成棧頂部，即要遵照後進先出（LIFO）的原則。

棧與哈希表同樣既不是強類型也不限制元素個數。

Push 操做

 1: //Stack is LIFO: Last in First Out

 2:  System.Collections.Stack objStackPush = new System.Collections.Stack();

3:

 4:  //By Push method you can insert item at the top of the stack

 5:  objStackPush.Push("Mahsa");

 6:  objStackPush.Push("Hassankashi");

 7:  this.lblPop.Text = "";

 8:  this.ListBoxStack.DataSource = objStackPush.ToArray();

 9:  this.ListBoxStack.DataBind();

Pop操做

 1: System.Collections.Stack objStackPop = new System.Collections.Stack();

2:

 3: objStackPop.Push("Mahsa");

 4: objStackPop.Push("Hassankashi");

5:

 6: //By Pop method you can remove item from the top of the stack --> Last in First in

 7: this.lblPop.Text = objStackPop.Pop().ToString();

8:

 9: this.ListBoxStack.DataSource = objStackPop.ToArray();

 10: this.ListBoxStack.DataBind();

Queue

Queue同棧同樣也是具備優先級定義的結構體，遵循的規則是先進先出（FIFO），既不是強類型也不具備固定的大小限制。

入隊操做

 1: //Queue is FIFO: First in First Out

 2: System.Collections.Queue objQueue = new System.Collections.Queue();

3:

 4: //By Enqueue method you can insert item at the END of the Queue

 5: objQueue.Enqueue("Mahsa");

 6: objQueue.Enqueue("Hassankashi");

 7: objQueue.Enqueue("Cosmic");

 8: objQueue.Enqueue("Verse");

9:

 10: this.lblQueue.Text = "";

 11: this.ListBoxQueue.DataSource = objQueue.ToArray();

 12: this.ListBoxQueue.DataBind();

出隊操做

 1: System.Collections.Queue objQueue = new System.Collections.Queue();

2:

 3: objQueue.Enqueue("Mahsa");

 4: objQueue.Enqueue("Hassankashi");

 5: objQueue.Enqueue("Cosmic");

 6: objQueue.Enqueue("Verse");

7:

 8: //By Dequeue method you can remove item from the BEGINING of the Queue --> First in First out FIFO

 9: this.lblQueue.Text=objQueue.Dequeue().ToString();

10:

 11: this.ListBoxQueue.DataSource = objQueue.ToArray();

 12: this.ListBoxQueue.DataBind();

入隊操做

 1: System.Collections.Queue objQueue = new System.Collections.Queue();

2:

 3: objQueue.Enqueue("Mahsa");

 4: objQueue.Enqueue("Hassankashi");

 5: objQueue.Enqueue("Cosmic");

 6: objQueue.Enqueue("Verse");

7:

 8: //By Dequeue method you can remove item from the BEGINING of the Queue --> First in First out FIFO

 9: this.lblQueue.Text=objQueue.Dequeue().ToString();

10:

 11: this.ListBoxQueue.DataSource = objQueue.ToArray();

 12: this.ListBoxQueue.DataBind();

List

什麼狀況下須要使用List？

1. List長度可不固定

2. 當數據爲通用類型，List是強類型，List中元素類型不須要等到運行時來肯定，這種特性使得List 運行時效率很是高。

3. 可以使用Foreach關鍵字。

由於List不須要設定固定的大小，List靈活度高，且效率高經常使用於開發過程當中。

 1: //Like Array is Strong Type

 2: //Like ArrayList with No Dimension

 3: System.Collections.Generic.List<string> strList = new List<string>();

4:

5:

 6: strList.Add("Mahsa");

 7: strList.Add("Hassankashi");

 8: strList.Add("Cosmic");

 9: strList.Add("Verse");

10:

 11: this.ListBoxListGeneric.DataSource = strList;

 12: this.ListBoxListGeneric.DataBind();

13:

 14: System.Text.StringBuilder str = new System.Text.StringBuilder();

15:

 16: foreach (var item in strList)

 17: {

 18:  str.Append(" , " + item);

 19: }

 20: this.lblList.Text = str.ToString();

IList

IList 繼承了List，包含多種方法的List接口。若是你沒法判斷代碼改動的可能性，可使用IList接口，減小模塊之間的依賴性。IList是接口所以沒法被實例化，因此必須使用List來初始化。

 1: System.Collections.Generic.IList<string> strIList = new List<string>();

咱們一塊兒瞭解一下具體的類和接口之間的區別。

1. 具體類可繼承其餘類，並實現一個或多個接口。

2. 在內部類中能夠定義變量並賦值，接口中不容許此操做。

3. 具體類可包含構造函數，而接口中不能定義構造函數

4. 抽象類中可包含訪問修飾符如public,private等，接口中不能包含。

 1: //Ilist can not be instantiate from Ilist , so it should be instantiate from List

 2: System.Collections.Generic.IList<string> strIList = new List<string>();

3:

 4: strIList.Add("Mahsa");

 5: strIList.Add("Hassankashi");

 6: strIList.Add("Cosmic");

 7: strIList.Add("Verse");

8:

9:

 10: this.ListBoxListGeneric.DataSource = strIList;

 11: this.ListBoxListGeneric.DataBind();

12:

 13: System.Text.StringBuilder str = new System.Text.StringBuilder();

14:

 15: foreach (var item in strIList)

 16: {

 17:  str.Append(" , " + item);

 18: }

 19: this.lblList.Text = str.ToString();

IEnumerable

IEnumerable經常使用於遍歷集合元素，可是沒法修改（刪除或添加）數據，使用IEnumberable 會從服務器端將全部數據拷貝到客戶端，並進行必定的過濾，若是服務器端有大量數據會形成內存負載超重。

 1: //IEnumerable can not be instantiate from Enumerable , so it should be instantiate from List

 2:  System.Collections.Generic.IEnumerable<Employee> empIEnumerable = new List<Employee>

 3:  { new Employee { ID = 1001, Name="Mahsa"},

 4:  new Employee { ID = 1002, Name = "Hassankashi" },

 5:  new Employee { ID = 1003, Name = "CosmicVerse" },

 6:  new Employee { ID = 1004, Name = "Technical" }

 7:  };

8:

9:

 10:  this.GridViewIEnumerable.DataSource = empIEnumerable;

 11:  this.GridViewIEnumerable.DataBind();

12:

 13:  System.Text.StringBuilder str = new System.Text.StringBuilder();

14:

 15:  foreach (Employee item in empIEnumerable)

 16:  {

 17:  str.Append(" , " + item.ID +"-"+item.Name);

 18:  }

19:

 20:  this.lblIEnumerable.Text = str.ToString();

IQueryable

IQueryable與IEnumberable不一樣的是，當從服務器端加載過量的數據，IQueryable會自動減小應用負載。IQueryable可保證大數據量時應用程序的高性能。

IQueryable會先過濾數據，而後發送給客戶端。

 1: DataAccessEntities ctx = new DataAccessEntities();

 2:  var ctx = new DataAccessEntities();

 1: //Difference between IQueryable and IEnumerable

2:

 3:  //You can instantiate IEnumerable from List

4:

 5:  IEnumerable<employee> queryIEnumerable = new List<employee>() ;

6:

7:

 8:  //Bring ALL records from server --> to client then filter collection

 9:  //To bring all data from server you should omit where cluse from linq to sql

 10:  queryIEnumerable = from m in ctx.Employees select m;

11:

 12:  //If you use where as extension method with IEnumerable then All records will be loaded

 13:  queryIEnumerable = queryIEnumerable.Where(x => x.ID == 1).ToList();

14:

15:

16:

 17:  //You can not instantiate IQueryable

18:

 19:  IQueryable<employee> queryIQueryable=null;

20:

 21:  //Bring just ONE record from server --> to client

22:

 23:  queryIQueryable = (from m in ctx.Employees

 24:  where m.ID == 1

 25:  select m);

26:

 27:  //Whenever you call IQueryable so ==> It will be executed

 28:  this.GridViewIQueryable.DataSource = queryIQueryable.ToList();

 29:  this.GridViewIQueryable.DataBind();

 30: </employee>

SQL Profiler:

如何追蹤查詢語句生成TSQL，生成須要的數據結構體：

Step 1:

Start -> MS SQL Server 2008 -> Performance Tools -> SQL Server Profiler

Step 2:

SQL Server Profiler -> File -> New Trace

Step 3:

輸入鏈接數據庫的用戶名和密碼

Step 4:

General (Tab) -> Use the Template: Standard

Step 5:

Event Selection (Tab) -> Event : TSQL -> Select : SQL-BatchCompleted | Select Show all Columns

Press Column Filter -> Database Name: Like: "DataAccess"

運行

Step 6:

查看結果

Step 7:

生成 IEnumerable數據 :

 1: SELECT

 2: [Extent1].[ID] AS [ID],

 3: [Extent1].[Name] AS [Name],

 4: [Extent1].[Age] AS [Age]

 5: FROM [dbo].[Employee] AS [Extent1]

生成 IQueryable :

SELECT 
[Extent1].[ID] AS [ID], 
[Extent1].[Name] AS [Name], 
[Extent1].[Age] AS [Age]
FROM [dbo].[Employee] AS [Extent1]
WHERE 1 = [Extent1].[ID]

ICollection 繼承了IEnumberable，可是IEnumberable是基於索引的，ICollection不基於索引。

 1: //IList {indexer and Modify} vs ICollection {randomly and Modify}

 2:  //Collection can not be instantiate from ICollection , so it should be instantiate from List

 3:  System.Collections.Generic.ICollection<string> strICollection = new List<string>();

 4:  strICollection.Add("Mahsa");

 5:  strICollection.Add("Hassankashi");

6:

 7:  //Countable***

 8:  int ICollectionCount=strICollection.Count;

9:

 10:  this.ListBoxICollection.DataSource = strICollection;

 11:  this.ListBoxICollection.DataBind();

 12:  System.Text.StringBuilder str = new System.Text.StringBuilder();

 13:  foreach (var item in strICollection)

 14:  {

 15:  str.Append(" , " + item);

 16:  }

 17:  this.lblICollection.Text = str.ToString();

18:

 19:  //IList***

 20:  System.Collections.Generic.IList<Employee> objIList = new List<Employee>();

 21:  objIList = (from m in ctx.Employees

 22:  select m).ToList();

23:

 24: Employee obj = objIList.Where(i => i.Name == "Sara").FirstOrDefault();

 25: int indexofSara= objIList.IndexOf(obj);

 26: int cIList = objIList.Count;

27:

 28:  //ICollection***

 29:  System.Collections.Generic.ICollection<Employee> objICollection = new List<Employee>();

 30:  objICollection = (from m in ctx.Employees

 31:  select m).ToList();

 32:  Employee objIC = objICollection.Where(i => i.Name == "Sara").FirstOrDefault();

 33:  //You can not get index of object , if you clear comment from below code appears error

 34: // int indexofSaraICollection = objIC.IndexOf(objIC);

 35:  int cICollection = objICollection.Count;

Stack Generic

入棧：

 1: //Stack is LIFO: Last in First Out

 2:  //Here is for Push Stack in Generic

 3:  //System.Collections.Stack objStackPush = new System.Collections.Stack();

 4:  //Stack<T> can be instantiated from Stack<T>

5:

 6:  System.Collections.Generic.Stack<int> objStackPush = new System.Collections.Generic.Stack<int>();

7:

 8:  objStackPush.Push(1);

 9:  objStackPush.Push(2);

10:

 11:  this.lblPopGeneric.Text = "";

 12:  this.ListBoxStackGeneric.DataSource = objStackPush.ToArray();

 13:  this.ListBoxStackGeneric.DataBind();

出棧：

 1: //Stack is LIFO: Last in First Out

 2:  //Here is for Pop Stack in Generic

 3:  //System.Collections.Stack objStackPop = new System.Collections.Stack();

 4:  //Stack<T> can be instantiated from Stack<T>

5:

 6:  System.Collections.Generic.Stack<int> objStackPop = new System.Collections.Generic.Stack<int>();

7:

 8:  objStackPop.Push(1);

 9:  objStackPop.Push(2);

10:

 11:  this.lblPop.Text = objStackPop.Pop().ToString();

 12:  this.ListBoxStack.DataSource = objStackPop.ToArray();

 13:  this.ListBoxStack.DataBind();

Queue Generic

入隊：

 1: //Queue is FIFO: First in First Out

 2:  //Here is for Enqueue Queue in Generic

 3:  //System.Collections.Queue objQueue = new System.Collections.Queue();

 4:  //Queue<T> can be instantiated from Queue<T>

5:

 6:  System.Collections.Generic.Queue<int> objQueue = new System.Collections.Generic.Queue<int>();

 7:  objQueue.Enqueue(1);

 8:  objQueue.Enqueue(2);

9:

 10:  this.lblQueue.Text = "";

11:

 12:  this.ListBoxQueue.DataSource = objQueue.ToArray();

 13:  this.ListBoxQueue.DataBind();

出隊：

 1: //Queue is FIFO: First in First Out

 2:  //Here is for Enqueue Queue in Generic

 3:  //System.Collections.Queue objQueue = new System.Collections.Queue();

 4:  //Queue<T> can be instantiated from Queue<T>

5:

 6:  System.Collections.Generic.Queue<int> objQueue = new System.Collections.Generic.Queue<int>();

 7:  objQueue.Enqueue(1);

 8:  objQueue.Enqueue(2);

9:

 10:  this.lblQueue.Text = "";

11:

 12:  this.ListBoxQueue.DataSource = objQueue.ToArray();

 13:  this.ListBoxQueue.DataBind();

Dictionary 及 IDictionary：

Dictionary 可通用，而哈希表不是通用的。Dictionary定義 <TKey，Tvalue>。IDictionary是Dictionary的接口，若是在後期開發中須要大量修改，建議使用IDictionary。

//Dictionary can instantiate from Dictionary , Dictionary is similar to Hashtable, //Dictionary is GENERIC but Hashtable is NON GENERIC //Such Hashtable you can find object by its key System.Collections.Generic.Dictionary<int, string=""> objDictionary = new Dictionary<int, string="">();

objDictionary.Add(1001, "Mahsa");
objDictionary.Add(1002, "Hassankashi");
objDictionary.Add(1003, "Cosmicverse"); string str = objDictionary[1002]; this.ListBoxDictionary.DataSource = objDictionary; this.ListBoxDictionary.DataBind();</int,>

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