GC::GetGeneration Method (WeakReference^)

 

Returns the current generation number of the target of a specified weak reference.

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

public:
static int GetGeneration(
	WeakReference^ wo
)

Parameters

wo
Type: System::WeakReference^

A WeakReference that refers to the target object whose generation number is to be determined.

Return Value

Type: System::Int32

The current generation number of the target of wo.

Exception Condition
ArgumentException

Garbage collection has already been performed on wo.

The following example demonstrates the use of the GetGeneration method to determine the age of a weak reference object.

using namespace System;
ref class MyGCCollectClass
{
private:
   static const long maxGarbage = 1000;

public:
   void MakeSomeGarbage()
   {
      Version^ vt;
      for ( int i = 0; i < maxGarbage; i++ )
      {

         // Create objects and release them to fill up memory
         // with unused objects.
         vt = gcnew Version;

      }
   }

};

int main()
{

   // Create a strong reference to an Object.
   MyGCCollectClass^ myGCCol = gcnew MyGCCollectClass;

   // Put some objects in memory.
   myGCCol->MakeSomeGarbage();

   // Get the generation of managed memory where myGCCol is stored.
   Console::WriteLine( "The object is in generation: {0}", GC::GetGeneration( myGCCol ) );

   // Perform a full garbage collection.
   // Because there is a strong reference to myGCCol, it will
   // not be garbage collected.
   GC::Collect();

   // Get the generation of managed memory where myGCCol is stored.
   Console::WriteLine( "The object is in generation: {0}", GC::GetGeneration( myGCCol ) );

   // Create a WeakReference to myGCCol.
   WeakReference^ wkref = gcnew WeakReference( myGCCol );

   // Remove the strong reference to myGCCol.
   myGCCol = nullptr;

   // Get the generation of managed memory where wkref is stored.
   Console::WriteLine( "The WeakReference to the object is in generation: {0}", GC::GetGeneration( wkref ) );

   // Perform another full garbage collection.
   // A WeakReference will not survive a garbage collection.
   GC::Collect();

   // Try to get the generation of managed memory where wkref is stored.
   // Because it has been collected, an exception will be thrown.
   try
   {
      Console::WriteLine( "The WeakReference to the object is in generation: {0}", GC::GetGeneration( wkref ) );
      Console::Read();
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "The WeakReference to the object has been garbage collected: ' {0}'", e );
   }

}

.NET Framework
Available since 1.1
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