hi im c++ beginner, can u give me some advice to improve this code.

[detorresrc]

#include <iostream>
#include <mysql.h>

using namespace std;

struct MySQLRS{
public:
	MySQLRS(MYSQL *pMySQL);
	~MySQLRS();
	MYSQL_RES *ptrResult;
	MYSQL_ROW row;
	MYSQL_FIELD *ptrField;
	void setTotalRows(int pnTotalRows);
	int getTotalRows();
	int isEOF();
	void setEOF(bool pnEOF);
	void moveNext();
	void freeResult();
private:
	MYSQL *ptrMySQL;
	long _nTotalRows;
	int _nCurrentRow;
	bool _bEOF;
};

void MySQLRS::freeResult(){
	mysql_free_result( ptrResult  );
	return;
}

void MySQLRS::setEOF(bool pnEOF){
	_bEOF = pnEOF;
	return;
};

int MySQLRS::isEOF(){
	return _bEOF;
};

void MySQLRS::setTotalRows(int pnTotalRows){
	_nTotalRows = pnTotalRows;
};

int MySQLRS::getTotalRows(){
	return _nTotalRows;
};

void MySQLRS::moveNext(){
	if( (_nCurrentRow + 1) >= _nTotalRows ){
		MySQLRS::freeResult();
		_bEOF = true;
	}else{
		mysql_data_seek(ptrResult, _nCurrentRow + 1);
		row = mysql_fetch_row(ptrResult);
		if( row == NULL ){
			MySQLRS::freeResult();
			_bEOF = true;
		}else{
			_nCurrentRow++;
		}
	}
};

MySQLRS::MySQLRS(MYSQL *pMySQL){
	ptrResult=0; ptrField=0; _nTotalRows=0; _nCurrentRow=0; _bEOF=false; row=NULL;
	ptrMySQL = pMySQL;
};

MySQLRS::~MySQLRS(){
	delete ptrResult; ptrResult=0; delete ptrField; ptrField=0;
};

typedef struct MySQLRS *ptrMySQLRS;

class MySQL{
public:
	MySQL();
	~MySQL();
	string sHostName;
	string sUserName;
	string sPassword;
	string sErrorMsg;
	int    nErrorNo;
	string sDatabase;
	int Connect(string psHostName, string psUserName, string psPassword, string psDatabase);
	void Close();
	int Query(char *psQuery);
	ptrMySQLRS Execute(char *psQuery);

	MYSQL *ptrMYSQL;
};

ptrMySQLRS MySQL::Execute(char *psQuery){
	ptrMySQLRS RS;
	RS = new MySQLRS(ptrMYSQL);
	if( mysql_query(ptrMYSQL, psQuery) != 0  ){
		sErrorMsg = mysql_error(ptrMYSQL);
		nErrorNo  = mysql_errno(ptrMYSQL);
		RS->setEOF(true);
	}else{
		RS->ptrResult = mysql_store_result(ptrMYSQL);
		RS->setTotalRows( (long)mysql_num_rows (RS->ptrResult) );
		RS->row = mysql_fetch_row(RS->ptrResult);
		if(RS->getTotalRows() > 0){
			RS->setEOF(false);	
		}
	}
	return RS;
};

MySQL::MySQL(){
	sHostName="";sUserName="";sPassword="";sErrorMsg="";sDatabase="";
	ptrMYSQL = 0;
};

MySQL::~MySQL(){
	MySQL::Close();
	delete ptrMYSQL; ptrMYSQL=0;
};

int MySQL::Connect(string psHostName, string psUserName, string psPassword, string psDatabase){
	sHostName = psHostName;
	sUserName = psUserName;
	sPassword = psPassword;
	sDatabase = psDatabase;

	ptrMYSQL = mysql_init(NULL);
	if(ptrMYSQL == NULL){
		sErrorMsg = "mysql_init() Error";
		return 0;
	}
	if(!mysql_real_connect(ptrMYSQL, MySQL::sHostName.c_str(), MySQL::sUserName.c_str(), MySQL::sPassword.c_str(), MySQL::sDatabase.c_str(), 0, NULL, 0)){
		sErrorMsg = mysql_error(ptrMYSQL);
		nErrorNo  = mysql_errno(ptrMYSQL);
		return 0;
	}
	return 1;
};

void MySQL::Close(){
	mysql_close(ptrMYSQL);
};

int MySQL::Query(char *psQuery){
	if(mysql_query(ptrMYSQL, psQuery) != 0){
		sErrorMsg = mysql_error(ptrMYSQL);
		nErrorNo  = mysql_errno(ptrMYSQL);
		return 0;
	}
	return 1;
}


int main(int argc, char *args[]){
	MySQL *ptrMySQL = new MySQL;
	MySQL *ptrMySQL2 = new MySQL;
	MySQLRS *RS = 0;	
	MySQLRS *RS2 = 0;
	char sQuery[200];

	ptrMySQL->Connect("localhost", "root", "", "tones_config");
	ptrMySQL2->Connect("localhost", "root", "", "tones_config");
	
	RS = ptrMySQL->Execute("SELECT * FROM keyword_list LIMIT 5");
	while( !RS->isEOF() ){
		cout << "RS1 => " << RS->row[0] << endl;
		RS2 = ptrMySQL2->Execute("SELECT * FROM keyword_list LIMIT 5");
		while(!RS2->isEOF()){
			cout << "RS2 => " << RS2->row[0] << endl;
			RS2->moveNext();
		}
		cout << endl << endl;
		RS->moveNext();
	}
	delete RS; RS=0;
	delete RS2; RS2=0;
	delete ptrMySQL; ptrMySQL=0;
	delete ptrMySQL2; ptrMySQL2=0;
	return 0;
}

hi im c++ beginner, can u give me some advice to improve this code. Thanks. :)

[ropez]

From a quick look, it seems fine.

Only a few comments, line 159:

char sQuery[200];

A hard-coded buffer size like this can cause trouble. However, you don't use this buffer, so you should remove this line.

Various places:

Query(char *psQuery)

The mysql library probably use const char* parameters, and you should do that too, since your functions doesn't write to these character buffers.

Typedef for pointer:

typedef struct MySQLRS *ptrMySQLRS;

IMHO, you should never create a typedef just to hide the pointer syntax. Stick with MySQLRS*. And btw, in C++, you don't need to use the struct keyword with your struct name.

Manual memory resource handling in main:

MySQL *ptrMySQL = new MySQL;
// ...
delete ptrMySQL;

In this case, you don't need to allocate like this, but you can do this:

MySQL mySQL;
// ...
// No need to delete 

However, that doesn't work for the result sets, so I would suggest using std::auto_ptr instead:

#include <memory>
// ...
auto_ptr<MySQLRS> rs;
// ...
rs.reset(ptrMySQL->Execute(...));
// ...
rs->doStuff();
// ...
// No need to delete 

[detorresrc]

sir can u rewrite this program and make it simple. thanks