Stack::Synchronized Method (Stack^)


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

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

[HostProtectionAttribute(SecurityAction::LinkDemand, Synchronization = true)]
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.

Exception Condition

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 = gcnew Stack();
bool lockTaken = false;
    Monitor::Enter(myCollection->SyncRoot, lockTaken);
    for each (Object^ item in myCollection);
        // Insert your code here.
    if (lockTaken)

This method is an O(1) operation.

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

#using <system.dll>

using namespace System;
using namespace System::Collections;
int main()

   // Creates and initializes a new Stack.
   Stack^ myStack = gcnew 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 ? (String^)"synchronized" : "not synchronized" );
   Console::WriteLine( "mySyncdStack is {0}.", mySyncdStack->IsSynchronized ? (String^)"synchronized" : "not synchronized" );

This code produces the following output.

myStack is not synchronized.
mySyncdStack is synchronized.

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
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