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Synchronized Method

Stack.Synchronized Method

Returns a synchronized (thread safe) wrapper for the Stack.

Namespace:  System.Collections
Assembly:  mscorlib (in mscorlib.dll)

[HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization = true)]
public static Stack Synchronized(
	Stack stack


Type: System.Collections.Stack

The Stack to synchronize.

Return Value

Type: System.Collections.Stack
A synchronized wrapper around the Stack.


stack is null.

To guarantee the thread safety of the Stack, all operations must be done through this wrapper.

Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

The following code example shows how to lock the collection using the SyncRoot during the entire enumeration.

Stack myCollection = new Stack();

    foreach (object item in myCollection)
        // Insert your code here.

This method is an O(1) operation.


The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: Synchronization. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The following example shows how to synchronize a Stack, determine if a Stack is synchronized, and use a synchronized Stack.

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" );

       // Creates a synchronized wrapper around the Stack.
       Stack mySyncdStack = Stack.Synchronized( myStack );

       // Displays the sychronization status of both Stacks.
       Console.WriteLine( "myStack is {0}.",
          myStack.IsSynchronized ? "synchronized" : "not synchronized" );
       Console.WriteLine( "mySyncdStack is {0}.",
          mySyncdStack.IsSynchronized ? "synchronized" : "not synchronized" );
 This code produces the following output.

 myStack is not synchronized.
 mySyncdStack is synchronized.

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0
© 2015 Microsoft