Identifying memory leaks in C++

Programmer Question

I've got the following bit of code, which I've narrowed down to be causing a memory leak (that is, in Task Manager, the Private Working Set of memory increases with the same repeated input string). I understand the concepts of heaps and stacks for memory, as well as the general rules for avoiding memory leaks, but something somewhere is still going wrong:

while(!quit){
   char* thebuffer = new char[210]; 
   //checked the function, it isn't creating the leak
   int size = FuncToObtainInputTextFromApp(thebuffer); //stored in thebuffer
   string bufferstring = thebuffer;
   int startlog = bufferstring.find("$");
   int endlog = bufferstring.find("&");
   string str_text="";
   str_text = bufferstring.substr(startlog,endlog-startlog+1);
   String^ str_text_m = gcnew String(str_text_m.c_str());
   //some work done
   delete str_text_m;
   delete [] thebuffer; 
}

The only thing I can think of is it might be the creation of 'string str_text' since it never goes out of scope since it just reloops in the while? If so, how would I resolve that? Defining it outside the while loop wouldn't solve it since it'd also remain in scope then too. Any help would be greatly appreciated.

Find the answer here