void reset(  
   _element_type _new_ptr = nullptr  
);  

// msl_auto_gcroot_reset.cpp  
// compile with: /clr  
#include <msclr\auto_gcroot.h>  
  
using namespace System;  
using namespace msclr;  
  
ref class ClassA {  
   String^ m_s;  
public:  
   ClassA( String^ s ) : m_s( s ) {  
      Console::WriteLine( "ClassA constructor: " + m_s );  
   }  
   ~ClassA() {  
      Console::WriteLine( "ClassA destructor: " + m_s );  
   }  
  
   void PrintHello() {  
      Console::WriteLine( "Hello from {0} A!", m_s );  
   }  
};  
  
int main()  
{  
   auto_gcroot<ClassA^> agc1 = gcnew ClassA( "first" );  
   agc1->PrintHello();  
  
   ClassA^ ha = gcnew ClassA( "second" );  
   agc1.reset( ha ); // release first object, reference second  
   agc1->PrintHello();  
  
   agc1.reset(); // release second object, set to nullptr  
  
   Console::WriteLine( "done" );  
}  

ClassA constructor: first  
Hello from first A!  
ClassA constructor: second  
ClassA destructor: first  
Hello from second A!  
ClassA destructor: second  
done