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.NET Forum / Languages / Managed C++ / May 2005

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Object reference not set to an instance of an object error

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xactdata - 25 May 2005 21:13 GMT
I have a program that uses the OleDbConnection class using C++.NET. I have
all of the appropriate includes, namespaces, references, etc. and declare the
class:

class OleDBClass {
public:
 gcroot<OleDbConnection*> oleConn;
 OleDBClass( ) {}
};

inside my application class. It builds just fine with that. Now I want to
open a new OleDbConnection with the following in my application class
InitInstance method:

OleDBClass *oleDBCONN;
oleDBCONN->oleConn->ConnectionString =
"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=<some database name>;User
Id=admin;Password=";
oleDBCONN->oleConn->Open();

When I run it I get the error "Object reference not set to an instance of an
object", on the oleDBCONN->oleConn->ConnectionString call.

Any help would be greatly appreciated.

Thanks
Tomas Restrepo \(MVP\) - 26 May 2005 03:15 GMT
>I have a program that uses the OleDbConnection class using C++.NET. I have
> all of the appropriate includes, namespaces, references, etc. and declare
[quoted text clipped - 16 lines]
> Id=admin;Password=";
> oleDBCONN->oleConn->Open();

You're declaring the variable for the connection, but never actually
initializing it... At the least, do:

class OleDBClass {
public:
   gcroot<OleDbConnection*> oleConn;
   OleDBClass( ) { oleConn = new OleDbConnection(); }
};

Signature

Tomas Restrepo
tomasr@mvps.org
http://www.winterdom.com/


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