freeing resources

[billq]

Hello,
I am new to c# and have become confused about freeing resources. I need to
know if using an objects Dispose method does the same thing as setting the
object to null?

Pen bluePen = new Pen( Color.Blue, 2 );
//use pen
bluePen.Dispose();

as opposed to:

Pen bluePen = new Pen(Color.Blue, 2);
//use pen
bluePen = null;

I appreciate your help
thank you
bill

[Jianwei Sun]

No, it's different.

1Call dispose will explicitly release the resources and the resource
will be freed immediately.

2Set it to null will rely on the garbage collection to free it up.

The 1is the recommended way to free the resource.

billq wrote:

Hello,
I am new to c# and have become confused about freeing resources. I need to
know if using an objects Dispose method does the same thing as setting the
object to null?

Pen bluePen = new Pen( Color.Blue, 2 );
//use pen
bluePen.Dispose();

as opposed to:

Pen bluePen = new Pen(Color.Blue, 2);
//use pen
bluePen = null;

I appreciate your help
thank you
bill

[Roger]

Also, see Using statement (the one about freeing
resources).
Roger

I am new to c# and have become confused about freeing resources. I need

to

know if using an objects Dispose method does the same thing as setting the
object to null?

Pen bluePen = new Pen( Color.Blue, 2 );
//use pen
bluePen.Dispose();

as opposed to:

Pen bluePen = new Pen(Color.Blue, 2);
//use pen
bluePen = null;

I appreciate your help
thank you
bill

[Kevin Spencer]

This (the using statment) is an important point. If you use a class that
needs disposing, and it is not disposed, it can cause some serious problems,
depending on the class being used. A file that is opened, for example, will
cause the file to remain locked, until the app exits. So, it is important to
ensure that Disposable objects are Disposed. This *can* be done using
try/catch/finally, as in:

try
{
Pen bluePen = new Pen( Color.Blue, 2 );
//use pen
}
finally
{
if (bluePen != null) bluePen.Dispose();
}

However, if you use a using statement, it is much simpler:

using (Pen bluePen = new Pen(Color.Blue, 2)
{
//use pen
}

The using statement automatically disposes the object created when it passes
out of scope.

--
HTH,

Kevin Spencer
Microsoft MVP
Professional Chicken Salad Alchemist

What You Seek Is What You Get.

"Roger" <ro***@pcsrevenuecontrol.comwrote in message
news:%2****************@TK2MSFTNGP03.phx.gbl...

Also, see Using statement (the one about freeing
resources).
Roger

>I am new to c# and have become confused about freeing resources. I need

to

>know if using an objects Dispose method does the same thing as setting
the
object to null?

Pen bluePen = new Pen( Color.Blue, 2 );
//use pen
bluePen.Dispose();

as opposed to:

Pen bluePen = new Pen(Color.Blue, 2);
//use pen
bluePen = null;

I appreciate your help
thank you
bill