Enumerable.Single<TSource> Method (IEnumerable<TSource>)

Type Parameters

• TSource
  The type of the elements of source.

Parameters

• source
  Type: System.Collections.Generic.IEnumerable<TSource>
  An IEnumerable<T> to return the single element of.

Return Value

Type: TSource
The single element of the input sequence.

' Create an array that contains one item.
Dim fruits1() As String = {"orange"}

' Get the single item in the array.
Dim result As String = fruits1.Single()

' Display the result.
outputBlock.Text &= "First query: " & result & vbCrLf

      string[] fruits1 = { "orange" };

      string fruit1 = fruits1.Single();

      outputBlock.Text += fruit1 + "\n";

      /*
       This code produces the following output:

       orange
      */

      ' Create an array that contains two items.
      Dim fruits2() As String = {"orange", "apple"}

      result = String.Empty

      ' Try to get the 'single' item in the array.
      Try
         result = fruits2.Single()
      Catch ex As System.InvalidOperationException
         result = "The collection does not contain exactly one element."
      End Try

      ' Display the result.
      outputBlock.Text &= "Second query: " & result & vbCrLf

      ' This code produces the following output:
      '
      ' First query: orange
      ' Second query: The collection does not contain exactly one element.

      string[] fruits2 = { "orange", "apple" };
      string fruit2 = null;

      try
      {
         fruit2 = fruits2.Single();
      }
      catch (System.InvalidOperationException)
      {
         outputBlock.Text += "The collection does not contain exactly one element." + "\n";
      }

      outputBlock.Text += fruit2 + "\n";

      /*
       This code produces the following output:

       The collection does not contain exactly one element.
      */