Dynamically use of classes instances

  _RecordsetPtr pRst("ADODB.Recordset");
        // Connection String
		_bstr_t strCnn("DRIVER={Microsoft Access Driver (*.mdb)};UID="";DBQ=testBroker.mdb");
        	 // Open table
		
		pRst->Open("SELECT value_d, tag FROM medidasDigitais ", strCnn, adOpenStatic, adLockReadOnly, adCmdText);
        	 
		pRst->MoveFirst();


            	 while (!pRst->EndOfFile) {
		
// this is key point where i want to get the tag 
// and use methods associated with it
// note that the the instance of the class as been already 
// initialized	
		 (pRst->GetFields()->GetItem("tag")->GetValue()).ucState=(pRst->GetFields()->GetItem("value_d")->GetValue());
						 
            		    

						pRst->MoveNext();
            	 }
				 	
						pRst->Close();

#include <iostream>
#include <map>
#include <string>

class CRectangle {		// this a standard rectangle class see it on cplusplus.com/doc/tutorial/classes/
    int *width, *height;
  public:
	int value;  //   this is as just a test variable that it is suposed to be manipulated dynamacly
    CRectangle (int,int);
    ~CRectangle ();
    int area () {return (*width * *height);}

};

CRectangle::CRectangle (int a, int b) {
  width = new int;
  height = new int;
  value=0;   // check this value is to be 0
  *width = a;
  *height = b;
}

CRectangle::~CRectangle () {
  delete width;
  delete height;
}



using namespace std;

int main(){

	CRectangle *A;    // we have to create pointers if we want to use the -> operator
	A = new CRectangle (3,3);  // and then lets construct the class instance 
	CRectangle *B;
	B = new CRectangle (3,3);
	CRectangle *C;
	C = new CRectangle (3,3);
	CRectangle *D;
	D = new CRectangle (3,3);
	string strCin;

	map<string, CRectangle*> testMap;   // Inicializate the map whose name is going to be testMap
	
	testMap.insert(make_pair("A",A));  // .insert(PAIR TYPE HERE) receives type pair as input parameter
	testMap.insert(make_pair("B",B));  // make pair creates a pair of string, CRectangle (in this case)
	testMap.insert(make_pair("C",C));
	testMap.insert(make_pair("D",D));
	
	

	cout << "Enter wich rectangle do you want to know the area (A,B,C,D):" << endl;
	
	cin >> strCin;  // Instead of using a Cin we could get the value out of a database


	map<string, CRectangle*>::iterator it = testMap.find(strCin);

	// The .find() function returns an iterator to the matching key/value pair, or an iterator to the end of the map if key is not found. 

	cout << "First: " << it->first << " with size:" << it->first.length();


	// now here it comes the best part, we can actually access the functions, methods of a mapped class, how?

	// first find the class instance that you want with the find function already shown

	// second, now that you have the index in the iterator (that in this case has the name "it") you can use the objects first and second
	// to access the first type just do it->first and it will return the content of the string 
	// if you would want you could also do something like it->first.length() to get the lenght of the string
	// we have the hability to use all of the functions associated to the class string 



	cout << it->second->area() << endl;  // the second is the CRectangle in the map<string, CRectangle*>

	// we have access to the method area() because we had designed in line 11 as public
	
	cout <<"Value before: " <<it->second->value  <<endl;  // in the constructor the varaible value it is set to 0
								// so lets see if we can also access to public variables

	it->second->value=3;		// but we changed its value dynamicly to be 3
	
	cout << "Value after " <<it->second->value <<endl;	// and this is it, wow



	return 0;


/**************************************************  ****************************************
**************************************************  *****************************************
about: this is a test program written to demonstrate the use of maps on how to access
dynamacly created class instances, I hope it helps!!!
date: 06-07-2009
Author: Luis Mesquita
**************************************************  *****************************************
**************************************************  *****************************************/


}

class CRectangle {		// this a standard rectangle class see it on cplusplus.com/doc/tutorial/classes/
    int *width, *height;
  public:
	int value;  //   this is as just a test variable that it is suposed to be manipulated dynamacly
    CRectangle (int,int);
    ~CRectangle ();
    int area () {return (*width * *height);}
};

int main(){

	CRectangle *A;    // we have to create pointers if we want to use the -> operator
	A = new CRectangle (3,3);  // and then lets construct the class instance 

	map<string, CRectangle*>::iterator it = testMap.find(strCin);
	// The .find() function returns an iterator to the matching key/value pair, or an iterator to the end of the map if key is not found. 
	cout << "First: " << it->first << " with size:" << it->first.length();