LINQ series: LINQ-related features in C #

1. Anonymous type

By defining an anonymous type with the keyword VAR, the compiler emits a strong type based on the value of the expression on the right side of the operator.

Some basic rules to follow when using anonymous types:

◊ An anonymous type must have an initialization value, and the value cannot be null (NULL), because the type is inferred from the initializer;

◊ Anonymous types can be used for simple types, or for complex types. When defining a simple type, it is of little value. Compound anonymous types require a member declaration;

◊ Anonymous types cannot be used for fields of classes;

◊ An anonymous type can be used as an initializer in a for loop;

◊ You can use the new keyword; the initializer for the array must use the new keyword;

◊ Anonymous types can be used for arrays;

◊ all anonymous types are derived from the object type;

var " LINQ to Object ";

1.1 Compound anonymous Types

var product = new {Title = "LINQ to Object", UnitPrice = 10m};

1.2 Using anonymous types in For/foreach statements

var New int 1 1 2 3 5 8  -  +  };  for (var0; i < Fibonacci. Length; i++) {    Console.WriteLine (fibonacci[i]);}

var New int 1 1 2 3 5 8  -  +  }; foreach (varin fromwhere5Select  f) {    Console.WriteLine (number);}

1.3 Anonymous types and using

using var New SqlConnection (connectionString)) {    connection. Open ();     //  ......}

2. Array initializer

Initializes the array with the keyword new.

var New int 1 1 2 3 5 8  -  ;

3. Anonymous generic methods

func<Long,Long> factorial =Delegate(LongN) {    if(n = =1)    {        return 1; }    Longresult =1;  for(inti =2; I <= N; i++) {result*=i; }    returnresult;}; Console.WriteLine (Factorial (6));

//using System.Diagnostics;func<Long,Long> factorial =Delegate(LongN) {    returnn >1? n * (Long)(NewStackTrace (). GetFrame (0)        . GetMethod (). Invoke (NULL,New Object[] {n-1})): N;}; Console.WriteLine (Factorial (6));

4. Auto-Implement Properties

 Public string Get set; }

To set read-only properties:

 Public string Get Private set; }

5. Object and Collection initializers

Object initializer: Creates a new object in a declarative manner without invoking the constructor of the class, and sets the value of each property of the object.

New product{    1,    "LINQ to Object",    =  10m};

The collection initializer is used to initialize a collection.

New List<product> {     new1"LINQ to Object", UnitPrice = 10m},    new2"LINQ to ADO", UnitPrice =  20m}};

LINQ series: LINQ-related features in C #