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Sorting Data (C#)

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A sorting operation orders the elements of a sequence based on one or more attributes. The first sort criterion performs a primary sort on the elements. By specifying a second sort criterion, you can sort the elements within each primary sort group.

The following illustration shows the results of an alphabetical sort operation on a sequence of characters:

Graphic that shows an alphabetical sort operation.

The standard query operator methods that sort data are listed in the following section.

Methods

Method Name Description C# Query Expression Syntax More Information
OrderBy Sorts values in ascending order. orderby Enumerable.OrderBy

Queryable.OrderBy
OrderByDescending Sorts values in descending order. orderby … descending Enumerable.OrderByDescending

Queryable.OrderByDescending
ThenBy Performs a secondary sort in ascending order. orderby …, … Enumerable.ThenBy

Queryable.ThenBy
ThenByDescending Performs a secondary sort in descending order. orderby …, … descending Enumerable.ThenByDescending

Queryable.ThenByDescending
Reverse Reverses the order of the elements in a collection. Not applicable. Enumerable.Reverse

Queryable.Reverse

Query Expression Syntax Examples

Primary Sort Examples

Primary Ascending Sort

The following example demonstrates how to use the orderby clause in a LINQ query to sort the strings in an array by string length, in ascending order.

string[] words = { "the", "quick", "brown", "fox", "jumps" };  
  
IEnumerable<string> query = from word in words  
                            orderby word.Length  
                            select word;  
  
foreach (string str in query)  
    Console.WriteLine(str);  
  
/* This code produces the following output:  
  
    the  
    fox  
    quick  
    brown  
    jumps  
*/

Primary Descending Sort

The next example demonstrates how to use the orderby descending clause in a LINQ query to sort the strings by their first letter, in descending order.

string[] words = { "the", "quick", "brown", "fox", "jumps" };  
  
IEnumerable<string> query = from word in words  
                            orderby word.Substring(0, 1) descending  
                            select word;  
  
foreach (string str in query)  
    Console.WriteLine(str);  
  
/* This code produces the following output:  
  
    the  
    quick  
    jumps  
    fox  
    brown  
*/

Secondary Sort Examples

Secondary Ascending Sort

The following example demonstrates how to use the orderby clause in a LINQ query to perform a primary and secondary sort of the strings in an array. The strings are sorted primarily by length and secondarily by the first letter of the string, both in ascending order.

string[] words = { "the", "quick", "brown", "fox", "jumps" };  
  
IEnumerable<string> query = from word in words  
                            orderby word.Length, word.Substring(0, 1)  
                            select word;  
  
foreach (string str in query)  
    Console.WriteLine(str);  
  
/* This code produces the following output:  
  
    fox  
    the  
    brown  
    jumps  
    quick  
*/

Secondary Descending Sort

The next example demonstrates how to use the orderby descending clause in a LINQ query to perform a primary sort, in ascending order, and a secondary sort, in descending order. The strings are sorted primarily by length and secondarily by the first letter of the string.

string[] words = { "the", "quick", "brown", "fox", "jumps" };  
  
IEnumerable<string> query = from word in words  
                            orderby word.Length, word.Substring(0, 1) descending  
                            select word;  
  
foreach (string str in query)  
    Console.WriteLine(str);  
  
/* This code produces the following output:  
  
    the  
    fox  
    quick  
    jumps  
    brown  
*/

See also