I need a code that allows me to show a "Please Wait" Dialog while performing a lengthy operation

Question

Hi,
I have very basic knowledge of C++ and I don't understand completely how this works. I have been trying to use pthreads in order to be able to show a "Please Wait" Dialog while performing a lengthy operation. The problem is that the dialog
box is showing up with a blank box where the label should go. Could you please modify the following code so that the program does what I am looking for? (note that I have pasted the sections of the program I think are useful for someone to provide an answer).
void *run_optimization( void *ptr );
void *run_optimization( void *ptr )
Solution x = Optimizer(); // Lengthy operation
const int * const SolArray = x.getDiscreteSolution();
return 0;
namespace RCM {
private: System::Void button2_Click(System::Object^  sender, System::EventArgs^  e) {
Processing^ Proc = gcnew Processing();
Proc->Show(); // this is the "Please Wait" Dialog
pthread_t thread1;
int ret1;
ret1 = pthread_create( &thread1, NULL, run_optimization, NULL);
pthread_join( thread1, NULL);
Thank you!!
EDIT:
I have tried the following:
void *run_optimization( void ^ptr );
void *run_optimization( void ^ptr )
Processing^ Proc = (Processing ^)ptr;
Solution x = Optimizer(); // Lengthy operation
const int * const SolArray = x.getDiscreteSolution();
Proc->Close();
return 0;
namespace RCM {
private: System::Void button2_Click(System::Object^  sender, System::EventArgs^  e) {
Processing^ Proc = gcnew Processing();
pthread_t thread1;
int ret1;
ret1 = pthread_create( &thread1, NULL, run_optimization, (void *)Proc);
Proc->Show(); // this is the "Please Wait" Dialog
But I am getting the following error:
error C2440: 'type cast' : cannot convert from 'RCM::Processing ^' to 'void *'

Answer 1

Hi Shu!
It runs in windows. I am using Visual Studio 2010 (and I can't use another version) which still doesn't have the threads integrated as I have read. So I am using POSIX threads for windows. 
Regarding the other question, I don't really know what either of those (.net framework library or native API) mean. I am sorry but I am really new at this and really don't know much but I am doing my best because I have to get this done.
I only know basic C++ but had to use C++/CLI windows forms because of a code I integrated in my program for running macros in excel and it was in C++/CLI.
Thank you for your help!
You cannot pass a managed handle to void* (as you have discovered).
If you really want to use Posix threads, you probably need to make your Processing class a normal C++ class, not a C++/CLI ref class.
But the .NET way to do this would be to use a BackgroundWorker:
https://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker%28v=vs.110%29.aspx
David Wilkinson | Visual C++ MVP