How to get around this unassigned variable problem?

[Karl]

Hi all,

I have a piece code like this:

static void Main()
{
Utility db;
try
{//create db connection, fill dataset...
db = new Utility();

}
catch(Exception e)
{
MessageBox.Show("Exit...");
}

if( db != null) <--- .net does not like it.
{
Application.Run(new DataForm(db));
}

}
When compiling, .NET complains that db at "if( db != null)" is undefined.
But that what I want to test. How could I get around of this problem?

Thanks,

Karl

[Jon Skeet [C# MVP]]

Karl <Ka**@discussions.microsoft.com> wrote:

I have a piece code like this:

static void Main()
{
Utility db;
try
{//create db connection, fill dataset...
db = new Utility();

}
catch(Exception e)
{
MessageBox.Show("Exit...");
}

if( db != null) <--- .net does not like it.
{
Application.Run(new DataForm(db));
}

}
When compiling, .NET complains that db at "if( db != null)" is undefined.
But that what I want to test. How could I get around of this problem?

Set db to null to start with:

Utility db = null;

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Michael Giagnocavo [MVP]]

The problem is that you don't exit in the catch block, you only show a
message, and then continue on. Add a return after the exit block to ensure
that the unitialized variable won't be accessed.

Alternatively, you can do Utility db = null; -- However, that's not really
your intention, and the compiler can't find mistakes in your code (like this
one -- you'd use the null value later on and get a NullReferenceException).
-Michael
MVP

"Karl" <Ka**@discussions.microsoft.com> wrote in message
news:51**********************************@microsof t.com...

Hi all,

I have a piece code like this:

static void Main()
{
Utility db;
try
{//create db connection, fill dataset...
db = new Utility();

}
catch(Exception e)
{
MessageBox.Show("Exit...");
}

if( db != null) <--- .net does not like it.
{
Application.Run(new DataForm(db));
}

}
When compiling, .NET complains that db at "if( db != null)" is undefined.
But that what I want to test. How could I get around of this problem?

Thanks,

Karl

[Michael Giagnocavo [MVP]]

I read right over the db != null part :S. So it wouldn't throw an exception
later on. My mistake.

Either way still works in this sample though. :)

--
Michael Giagnocavo
MVP
www.atrevido.net

"Michael Giagnocavo [MVP]" <mg*******@atrevido.net> wrote in message
news:O2*************@TK2MSFTNGP12.phx.gbl...

The problem is that you don't exit in the catch block, you only show a
message, and then continue on. Add a return after the exit block to ensure
that the unitialized variable won't be accessed.

Alternatively, you can do Utility db = null; -- However, that's not really
your intention, and the compiler can't find mistakes in your code (like
this one -- you'd use the null value later on and get a
NullReferenceException).
-Michael
MVP

"Karl" <Ka**@discussions.microsoft.com> wrote in message
news:51**********************************@microsof t.com...

Hi all,

I have a piece code like this:

static void Main()
{
Utility db;
try
{//create db connection, fill dataset...
db = new Utility();

}
catch(Exception e)
{
MessageBox.Show("Exit...");
}

if( db != null) <--- .net does not like it.
{
Application.Run(new DataForm(db));
}

}
When compiling, .NET complains that db at "if( db != null)" is undefined.
But that what I want to test. How could I get around of this problem?

Thanks,

Karl