StringDictionary.ContainsValue(String) StringDictionary.ContainsValue(String) StringDictionary.ContainsValue(String) StringDictionary.ContainsValue(String) Method

定义

确定 StringDictionary 是否包含特定值。Determines if the StringDictionary contains a specific value.

public:
 virtual bool ContainsValue(System::String ^ value);
public virtual bool ContainsValue (string value);
abstract member ContainsValue : string -> bool
override this.ContainsValue : string -> bool
Public Overridable Function ContainsValue (value As String) As Boolean

参数

value
String String String String

要在 StringDictionary 中定位的值。The value to locate in the StringDictionary. 该值可以为 nullThe value can be null.

返回

如果 true 包含具有指定值的元素,则为 StringDictionary;否则为 falsetrue if the StringDictionary contains an element with the specified value; otherwise, false.

示例

下面的代码示例在中StringDictionary搜索元素。The following code example searches for an element in a StringDictionary.

#using <System.dll>

using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;
void PrintKeysAndValues( StringDictionary^ myCol )
{
   Console::WriteLine( "   KEY        VALUE" );
   IEnumerator^ enum0 = myCol->GetEnumerator();
   while ( enum0->MoveNext() )
   {
      DictionaryEntry^ de = safe_cast<DictionaryEntry^>(enum0->Current);
      Console::WriteLine( "   {0,-10} {1}", de->Key, de->Value );
   }

   Console::WriteLine();
}

int main()
{
   
   // Creates and initializes a new StringDictionary.
   StringDictionary^ myCol = gcnew StringDictionary;
   myCol->Add( "red", "rojo" );
   myCol->Add( "green", "verde" );
   myCol->Add( "blue", "azul" );
   
   // Displays the values in the StringDictionary.
   Console::WriteLine( "Initial contents of the StringDictionary:" );
   PrintKeysAndValues( myCol );
   
   // Searches for a key.
   if ( myCol->ContainsKey( "red" ) )
      Console::WriteLine( "The collection contains the key \"red\"." );
   else
      Console::WriteLine( "The collection does not contain the key \"red\"." );

   Console::WriteLine();
   
   // Searches for a value.
   if ( myCol->ContainsValue( "amarillo" ) )
      Console::WriteLine( "The collection contains the value \"amarillo\"." );
   else
      Console::WriteLine( "The collection does not contain the value \"amarillo\"." );

   Console::WriteLine();
}

/*
This code produces the following output.

Initial contents of the StringDictionary:
   KEY        VALUE
   green      verde
   red        rojo
   blue       azul

The collection contains the key "red".

The collection does not contain the value "amarillo".

*/
using System;
using System.Collections;
using System.Collections.Specialized;

public class SamplesStringDictionary  {

   public static void Main()  {

      // Creates and initializes a new StringDictionary.
      StringDictionary myCol = new StringDictionary();
      myCol.Add( "red", "rojo" );
      myCol.Add( "green", "verde" );
      myCol.Add( "blue", "azul" );

      // Displays the values in the StringDictionary.
      Console.WriteLine( "Initial contents of the StringDictionary:" );
      PrintKeysAndValues( myCol );

      // Searches for a key.
      if ( myCol.ContainsKey( "red" ) )
         Console.WriteLine( "The collection contains the key \"red\"." );
      else
         Console.WriteLine( "The collection does not contain the key \"red\"." );
      Console.WriteLine();

      // Searches for a value.
      if ( myCol.ContainsValue( "amarillo" ) )
         Console.WriteLine( "The collection contains the value \"amarillo\"." );
      else
         Console.WriteLine( "The collection does not contain the value \"amarillo\"." );
      Console.WriteLine();

   }

   public static void PrintKeysAndValues( StringDictionary myCol )  {
      Console.WriteLine( "   KEY        VALUE" );
      foreach ( DictionaryEntry de in myCol )
         Console.WriteLine( "   {0,-10} {1}", de.Key, de.Value );
      Console.WriteLine();
   }

}

/*
This code produces the following output.

Initial contents of the StringDictionary:
   KEY        VALUE
   green      verde
   red        rojo
   blue       azul

The collection contains the key "red".

The collection does not contain the value "amarillo".

*/
Imports System.Collections
Imports System.Collections.Specialized

Public Class SamplesStringDictionary   

   Public Shared Sub Main()

      ' Creates and initializes a new StringDictionary.
      Dim myCol As New StringDictionary()
      myCol.Add("red", "rojo")
      myCol.Add("green", "verde")
      myCol.Add("blue", "azul")

      ' Displays the values in the StringDictionary.
      Console.WriteLine("Initial contents of the StringDictionary:")
      PrintKeysAndValues(myCol)

      ' Searches for a key.
      If myCol.ContainsKey("red") Then
         Console.WriteLine("The collection contains the key ""red"".")
      Else
         Console.WriteLine("The collection does not contain the key ""red"".")
      End If
      Console.WriteLine()

      ' Searches for a value.
      If myCol.ContainsValue("amarillo") Then
         Console.WriteLine("The collection contains the value ""amarillo"".")
      Else
         Console.WriteLine("The collection does not contain the value ""amarillo"".")
      End If
      Console.WriteLine()

   End Sub

   Public Shared Sub PrintKeysAndValues(myCol As StringDictionary)
      Dim de As DictionaryEntry

      Console.WriteLine("   KEY        VALUE")
      For Each de In  myCol
         Console.WriteLine("   {0,-10} {1}", de.Key, de.Value)
      Next de
      Console.WriteLine()

   End Sub

End Class


'This code produces the following output.
'
'Initial contents of the StringDictionary:
'   KEY        VALUE
'   green      verde
'   red        rojo
'   blue       azul
'
'The collection contains the key "red".
'
'The collection does not contain the value "amarillo".

注解

使用Object.Equals方法将 StringDictionary 的元素的值与指定的值进行比较。The values of the elements of the StringDictionary are compared to the specified value using the Object.Equals method.

此方法执行线性搜索;因此, 平均执行时间与成正比CountThis method performs a linear search; therefore, the average execution time is proportional to Count. 也就是说, 此方法是 O (n) 运算, 其中nCountThat is, this method is an O(n) operation, where n is Count.

从 .NET Framework 2.0 开始, 此方法使用Equals集合的对象的和CompareTo方法item来确定是否item存在。Starting with the .NET Framework 2.0, this method uses the collection's objects' Equals and CompareTo methods on item to determine whether item exists. 在 .NET Framework 的早期版本中, 此决定是通过对集合中的Equals对象CompareTo使用item参数的和方法进行的。In the earlier versions of the .NET Framework, this determination was made by using the Equals and CompareTo methods of the item parameter on the objects in the collection.

适用于

另请参阅