Stack.Pop Methode

Definition

Namespace:

System.Collections

Assembly:

System.Collections.NonGeneric.dll

Quelle:

Stack.cs

Entfernt das Objekt oben im Stack und gibt es zurück.

public:
 virtual System::Object ^ Pop();

public virtual object? Pop ();

abstract member Pop : unit -> obj
override this.Pop : unit -> obj

Public Overridable Function Pop () As Object

Gibt zurück

Object

Das Object, das von der obersten Position im Stack entfernt wurde.

Ausnahmen

InvalidOperationException

Die Stack ist leer.

Beispiele

Das folgende Beispiel zeigt, wie Sie Elemente zu Stackhinzufügen, Elemente aus dem Stackentfernen oder das Element am oberen Rand des Stackanzeigen.

using namespace System;
using namespace System::Collections;
void PrintValues( IEnumerable^ myCollection, char mySeparator );
int main()
{
   
   // Creates and initializes a new Stack.
   Stack^ myStack = gcnew Stack;
   myStack->Push( "The" );
   myStack->Push( "quick" );
   myStack->Push( "brown" );
   myStack->Push( "fox" );
   
   // Displays the Stack.
   Console::Write( "Stack values:" );
   PrintValues( myStack, '\t' );
   
   // Removes an element from the Stack.
   Console::WriteLine( "(Pop)\t\t{0}", myStack->Pop() );
   
   // Displays the Stack.
   Console::Write( "Stack values:" );
   PrintValues( myStack, '\t' );
   
   // Removes another element from the Stack.
   Console::WriteLine( "(Pop)\t\t{0}", myStack->Pop() );
   
   // Displays the Stack.
   Console::Write( "Stack values:" );
   PrintValues( myStack, '\t' );
   
   // Views the first element in the Stack but does not remove it.
   Console::WriteLine( "(Peek)\t\t{0}", myStack->Peek() );
   
   // Displays the Stack.
   Console::Write( "Stack values:" );
   PrintValues( myStack, '\t' );
}

void PrintValues( IEnumerable^ myCollection, char mySeparator )
{
   IEnumerator^ myEnum = myCollection->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ obj = safe_cast<Object^>(myEnum->Current);
      Console::Write( "{0}{1}", mySeparator, obj );
   }

   Console::WriteLine();
}

/* 
 This code produces the following output.
 
 Stack values:    fox    brown    quick    The
 (Pop)        fox
 Stack values:    brown    quick    The
 (Pop)        brown
 Stack values:    quick    The
 (Peek)        quick
 Stack values:    quick    The
 */

using System;
using System.Collections;
public class SamplesStack  {

   public static void Main()  {

      // Creates and initializes a new Stack.
      Stack myStack = new Stack();
      myStack.Push( "The" );
      myStack.Push( "quick" );
      myStack.Push( "brown" );
      myStack.Push( "fox" );

      // Displays the Stack.
      Console.Write( "Stack values:" );
      PrintValues( myStack, '\t' );

      // Removes an element from the Stack.
      Console.WriteLine( "(Pop)\t\t{0}", myStack.Pop() );

      // Displays the Stack.
      Console.Write( "Stack values:" );
      PrintValues( myStack, '\t' );

      // Removes another element from the Stack.
      Console.WriteLine( "(Pop)\t\t{0}", myStack.Pop() );

      // Displays the Stack.
      Console.Write( "Stack values:" );
      PrintValues( myStack, '\t' );

      // Views the first element in the Stack but does not remove it.
      Console.WriteLine( "(Peek)\t\t{0}", myStack.Peek() );

      // Displays the Stack.
      Console.Write( "Stack values:" );
      PrintValues( myStack, '\t' );
   }

   public static void PrintValues( IEnumerable myCollection, char mySeparator )  {
      foreach ( Object obj in myCollection )
         Console.Write( "{0}{1}", mySeparator, obj );
      Console.WriteLine();
   }
}


/*
This code produces the following output.

Stack values:    fox    brown    quick    The
(Pop)        fox
Stack values:    brown    quick    The
(Pop)        brown
Stack values:    quick    The
(Peek)        quick
Stack values:    quick    The
*/

Imports System.Collections

Public Class SamplesStack    

    Public Shared Sub Main()

        ' Creates and initializes a new Stack.
        Dim myStack As New Stack()
        myStack.Push("The")
        myStack.Push("quick")
        myStack.Push("brown")
        myStack.Push("fox")

        ' Displays the Stack.
        Console.Write("Stack values:")
        PrintValues(myStack, ControlChars.Tab)

        ' Removes an element from the Stack.
        Console.WriteLine("(Pop)" & ControlChars.Tab & ControlChars.Tab & _
           "{0}", myStack.Pop())

        ' Displays the Stack.
        Console.Write("Stack values:")
        PrintValues(myStack, ControlChars.Tab)

        ' Removes another element from the Stack.
        Console.WriteLine("(Pop)" & ControlChars.Tab & ControlChars.Tab & _
           "{0}", myStack.Pop())

        ' Displays the Stack.
        Console.Write("Stack values:")
        PrintValues(myStack, ControlChars.Tab)

        ' Views the first element in the Stack but does not remove it.
        Console.WriteLine("(Peek)" & ControlChars.Tab & ControlChars.Tab & _
           "{0}", myStack.Peek())

        ' Displays the Stack.
        Console.Write("Stack values:")
        PrintValues(myStack, ControlChars.Tab)

    End Sub

    Public Shared Sub PrintValues(myCollection As IEnumerable, mySeparator As Char)
        Dim obj As [Object]
        For Each obj In  myCollection
            Console.Write("{0}{1}", mySeparator, obj)
        Next obj
        Console.WriteLine()
    End Sub

End Class


' This code produces the following output.
' 
' Stack values:    fox    brown    quick    The
' (Pop)        fox
' Stack values:    brown    quick    The
' (Pop)        brown
' Stack values:    quick    The
' (Peek)        quick
' Stack values:    quick    The

Hinweise

Diese Methode ähnelt der Peek-Methode, aber Peek ändert die Stack nicht.

null kann bei Bedarf als Platzhalter auf die Stack geschoben werden. Um zwischen einem NULL-Wert und dem Ende des Stapels zu unterscheiden, überprüfen Sie die Count -Eigenschaft, oder fangen Sie den ab, der InvalidOperationExceptionausgelöst wird, wenn leer Stack ist.

Diese Methode ist ein O(1) Vorgang.

Weitere Informationen

• Peek()
• Push(Object)