Part of the 101 LINQ SAMPLES

Learn how to use LINQ in your applications with these code samples, covering the entire range of LINQ functionality and demonstrating LINQ with SQL, DataSets, and XML.

Browse all 101 LINQ Samples

Introduction

This sample shows different uses of Conversion Operators:

ToArray
ToList
ToDictionary
OfType

Building the Sample

Open the Program.cs
Comment or uncomment the desired samples
Press Ctrl + F5

Description

ToArray

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This sample uses ToArray to immediately evaluate a sequence into an array.

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public void Linq54()
{
    double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 };
 
    var sortedDoubles =
        from d in doubles
        orderby d descending
        select d;
    var doublesArray = sortedDoubles.ToArray();
 
    Console.WriteLine("Every other double from highest to lowest:");
    for (int d = 0; d < doublesArray.Length; d += 2)
    {
        Console.WriteLine(doublesArray[d]);
    }
}

public void Linq54() 
{ 
    double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 }; 
  
    var sortedDoubles = 
        from d in doubles 
        orderby d descending 
        select d; 
    var doublesArray = sortedDoubles.ToArray(); 
  
    Console.WriteLine("Every other double from highest to lowest:"); 
    for (int d = 0; d < doublesArray.Length; d += 2) 
    { 
        Console.WriteLine(doublesArray[d]); 
    } 
}

Result

Every other double from highest to lowest:
4.1
2.3
1.7

ToList

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This sample uses ToList to immediately evaluate a sequence into a List<T>.

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public void Linq55()
{
    string[] words = { "cherry", "apple", "blueberry" };
 
    var sortedWords =
        from w in words
        orderby w
        select w;
    var wordList = sortedWords.ToList();
 
    Console.WriteLine("The sorted word list:");
    foreach (var w in wordList)
    {
        Console.WriteLine(w);
    }
}

public void Linq55() 
{ 
    string[] words = { "cherry", "apple", "blueberry" }; 
  
    var sortedWords = 
        from w in words 
        orderby w 
        select w; 
    var wordList = sortedWords.ToList(); 
  
    Console.WriteLine("The sorted word list:"); 
    foreach (var w in wordList) 
    { 
        Console.WriteLine(w); 
    } 
}

Result

The sorted word list:
apple
blueberry
cherry

ToDictionary

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This sample uses ToDictionary to immediately evaluate a sequence and a related key expression into a dictionary.

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public void Linq56()
{
    var scoreRecords = new[] { new {Name = "Alice", Score = 50},
                                new {Name = "Bob"  , Score = 40},
                                new {Name = "Cathy", Score = 45}
                            };
 
    var scoreRecordsDict = scoreRecords.ToDictionary(sr => sr.Name);
 
    Console.WriteLine("Bob's score: {0}", scoreRecordsDict["Bob"]);
}

public void Linq56() 
{ 
    var scoreRecords = new[] { new {Name = "Alice", Score = 50}, 
                                new {Name = "Bob"  , Score = 40}, 
                                new {Name = "Cathy", Score = 45} 
                            }; 
  
    var scoreRecordsDict = scoreRecords.ToDictionary(sr => sr.Name); 
  
    Console.WriteLine("Bob's score: {0}", scoreRecordsDict["Bob"]); 
}

Result

Bob's score: { Name = Bob, Score = 40 }

OfType

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This sample uses OfType to return only the elements of the array that are of type double.

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public void Linq57()
{
    object[] numbers = { null, 1.0, "two", 3, "four", 5, "six", 7.0 };
 
    var doubles = numbers.OfType<double>();
 
    Console.WriteLine("Numbers stored as doubles:");
    foreach (var d in doubles)
    {
        Console.WriteLine(d);
    }
}

public void Linq57() 
{ 
    object[] numbers = { null, 1.0, "two", 3, "four", 5, "six", 7.0 }; 
  
    var doubles = numbers.OfType<double>(); 
  
    Console.WriteLine("Numbers stored as doubles:"); 
    foreach (var d in doubles) 
    { 
        Console.WriteLine(d); 
    } 
}

Result

Numbers stored as doubles:
1
7

Source Code Files

Program.cs

101 LINQ Samples

More Information

For more information, see:

Conversion Operators (C# Programming Guide) - http://msdn.microsoft.com/en-us/library/09479473(VS.80).aspx
Conversion Operators - http://msdn.microsoft.com/en-us/library/ms229033.aspx