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List:       mysql-plusplus
Subject:    Re: MYSQL++: Any ideas why this code causes the program to crash?
From:       Sinisa Milivojevic <sinisa () mysql ! com>
Date:       2001-06-18 10:20:05
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David Ayliffe writes:
> I wrote this program in VC++ using the MYSQL++ API for VC.  I have a
> generic function (below) which I call numerous times each time with a
> different query string.  It works fine the first time around.  But the
> second time I call this function it causes the program to crash.  I
> think it could be that a constructor is called but no deconstructor.
> Could this be the problem?  What deconstructor should I use??
> 
> I have trimmed the code for functionality:
> 
> <--CODE-->
> 
> void main()
> { bool j = ExecQuery("select * from stock"); }
> 
> 
> bool ExecQuery(string sQuery)
> {
> 	Connection con(def_db_name, def_host_name, def_user_name,
> def_password);
> 	Query query = con.query();
> 	// This creates a query object that is bound to con.
> 
> 	query << sQuery;
> 	// You can write to the query object like you would any other
> ostrem		
> 		
> 	cout << endl << "Query: " << query.preview() << endl;
> 	// Show the query before it is executed
> 	// Query::preview() simply returns a string with the current
> query
> 	// string in it.
> 		
> 	Result res = query.store();
> 	// Query::store() executes the query and returns the results
> 	
> 	Row row;
> 	cout.setf(ios::left);
> //	cout << setw(17) << "Database Name" << endl << endl;
>  
> 	Result::iterator i;
> 	
> 	for (i = res.begin(); i != res.end(); i++) 
> 	{
> 		row = *i;
> 		cout << setw(17)  << row[0] 
> 			<< setw(4)  << row[1] 
> 			<< setw(7)  << row[2]
> 			<< setw(7)  << row[3]
> 			<< row[4] << endl;			
> 	}
> 	cout << endl << "Records Found: " << res.size()  << endl;
> 
> 	return 1;
> }
> 
> <--END OF CODE-->
> 
> ANY INPUT APPRECIATED
> 
> Thanks lots
> David Ayliffe (mail@ayliffe.com)


Hi!

No, destructor is not a problem. In C++, you do not have to call
destructor except implicitely, e.g. with delete operator on dynamic
objects. 

In your program you only use local objects, so C++ itself generates
calls to destructors. 

Your problem is may be that you do send queries to the above method
that do not return result sets.


-- 
Regards,
   __  ___     ___ ____  __
  /  |/  /_ __/ __/ __ \/ /    Mr. Sinisa Milivojevic <sinisa@mysql.com>
 / /|_/ / // /\ \/ /_/ / /__   MySQL AB, FullTime Developer
/_/  /_/\_, /___/\___\_\___/   Larnaca, Cyprus
       <___/   www.mysql.com

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