CSharp - Returning a List So the Query Is Executed Immediately and the Results Are Cached

Description

Returning a List So the Query Is Executed Immediately and the Results Are Cached

Demo

using System;  
using System.Collections.Generic;
using System.Linq;  
class Program/*  ww  w  .  jav  a  2 s  . c om*/
{
    static void Main(string[] args)
    {
              //  Create an array of ints.  
              int[] intArray = new int[] { 1, 2, 3 };  
                
              List<int> ints = intArray.Select(i => i).ToList();  
                
              //  Display the results.  
              foreach(int i in ints)  
                Console.WriteLine(i);  
                
              // Change an element in the source data.  
              intArray[0] = 5;  
                
              Console.WriteLine("---------");  
                
              //  Display the results again.  
              foreach(int i in ints)  
                Console.WriteLine(i);  
                     
    }
}

Result

Notice the results do not change from one enumeration to the next.

This is because the ToList method is not deferred.

The query is actually performed at the time the query is called.

Related Topic

• Query Expressions
• Create Anonymous Types
• Collection Initialization on List
• Returning IEnumerable<T>, Yielding, and Deferred Queries
• Using One of the Func Delegate Declarations
• Query with Intentional Exception Deferred Until Enumeration
• Use the var Keyword When Confused
• XML Query Using LINQ to XML
• Database Query Using LINQ to SQL
• Converting an Array of Strings to Integers and Sorting It
• Get SQL query via DataContext Log
• Create extension for string to convert string to double and bool
• LINQ to Objects Query
• Query Results Changing Between Enumerations

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