use of unassigned local variable

[Ropo]

Newbie:
I am writing code to read an xml file. I want two values from the document
so I want to save them as I am reading through the elements. I want to
reference them (using Console.WriteLine) after I complete the loop. When I
compile I get the "use of unassigned local variable".

What am I doing wrong?

stripped down code:
static void Main()
{
string Msg;

try
{
// Open an XML file
XmlTextReader reader = new XmlTextReader("...");

while ( reader.Read() )
{
if (reader.NodeType == XmlNodeType.Whitespace)
continue;

if (reader.NodeType != XmlNodeType.EndElement )
{
Msg = reader.Value;
}

if (reader.HasAttributes)
{
reader.MoveToFirstAttribute();
}
}
}
catch (Exception e)
{
Console.WriteLine ("Exception: {0}", e.ToString());
}

Console.WriteLine(Msg);
}

[Paul Yanzick]

Not sure if this will help, but I have noticed in some cases that when I
define a variable in the function like that and use try, catch, or foreach
statements, it seems to loose scope. Assuming Msg is what is having the
problem during compile time, put it up in the definitions of the controls on
the page, or right under the class definition line and see if that works.

"Ropo" <Ro**@discussions.microsoft.com> wrote in message
news:24**********************************@microsof t.com...

Newbie:
I am writing code to read an xml file. I want two values from the document so I want to save them as I am reading through the elements. I want to
reference them (using Console.WriteLine) after I complete the loop. When I compile I get the "use of unassigned local variable".

What am I doing wrong?

stripped down code:
static void Main()
{
string Msg;

try
{
// Open an XML file
XmlTextReader reader = new XmlTextReader("...");

while ( reader.Read() )
{
if (reader.NodeType == XmlNodeType.Whitespace)
continue;

if (reader.NodeType != XmlNodeType.EndElement )
{
Msg = reader.Value;
}

if (reader.HasAttributes)
{
reader.MoveToFirstAttribute();
}
}
}
catch (Exception e)
{
Console.WriteLine ("Exception: {0}", e.ToString());
}

Console.WriteLine(Msg);
}

[Jon Skeet [C# MVP]]

Ropo <Ro**@discussions.microsoft.com> wrote:

I am writing code to read an xml file. I want two values from the document
so I want to save them as I am reading through the elements. I want to
reference them (using Console.WriteLine) after I complete the loop. When I
compile I get the "use of unassigned local variable".

What am I doing wrong?

<snip>

Well, consider the situation where an exception is thrown. It may be
thrown before Msg is ever assigned to - so what do you expect

Console.WriteLine (Msg);

at the end to do?

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

[Ropo]

Thanx, that helped.

I added 'static string Msg;' below the class definition and the value is
retrain.
"Paul Yanzick" wrote:

Not sure if this will help, but I have noticed in some cases that when I
define a variable in the function like that and use try, catch, or foreach
statements, it seems to loose scope. Assuming Msg is what is having the
problem during compile time, put it up in the definitions of the controls on
the page, or right under the class definition line and see if that works.

"Ropo" <Ro**@discussions.microsoft.com> wrote in message
news:24**********************************@microsof t.com...

Newbie:
I am writing code to read an xml file. I want two values from the

document

so I want to save them as I am reading through the elements. I want to
reference them (using Console.WriteLine) after I complete the loop. When

I

compile I get the "use of unassigned local variable".

What am I doing wrong?

stripped down code:
static void Main()
{
string Msg;

try
{
// Open an XML file
XmlTextReader reader = new XmlTextReader("...");

while ( reader.Read() )
{
if (reader.NodeType == XmlNodeType.Whitespace)
continue;

if (reader.NodeType != XmlNodeType.EndElement )
{
Msg = reader.Value;
}

if (reader.HasAttributes)
{
reader.MoveToFirstAttribute();
}
}
}
catch (Exception e)
{
Console.WriteLine ("Exception: {0}", e.ToString());
}

Console.WriteLine(Msg);
}

[Ropo]

the writeline is just a test to see if I can get the values at the end of the
loop. the main purpose is to send the Msg to an IM.

thanx

"Jon Skeet [C# MVP]" wrote:

Ropo <Ro**@discussions.microsoft.com> wrote:

I am writing code to read an xml file. I want two values from the document
so I want to save them as I am reading through the elements. I want to
reference them (using Console.WriteLine) after I complete the loop. When I
compile I get the "use of unassigned local variable".

What am I doing wrong?

<snip>

Well, consider the situation where an exception is thrown. It may be
thrown before Msg is ever assigned to - so what do you expect

Console.WriteLine (Msg);

at the end to do?

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

[Jon Skeet [C# MVP]]

Ropo <Ro**@discussions.microsoft.com> wrote:

the writeline is just a test to see if I can get the values at the end of the
loop. the main purpose is to send the Msg to an IM.

But in the code you've given, it's the WriteLine which is the problem.

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

[James Curran]

Basically, the error is says that it is possible for it to reach the
WriteLine(Msg); without MSg ever being assigned to. This would happen if
the first element was of type EndElement. Of course, that couldn't happen
in a proper XML file, but the compile doesn't know that. The simplest
solution is to just assign a value to Msg before you start.

string Msg = "";

--
Truth,
James Curran
Home: www.noveltheory.com Work: www.njtheater.com
Blog: www.honestillusion.com Day Job: www.partsearch.com
(note new day job!)
"Ropo" <Ro**@discussions.microsoft.com> wrote in message
news:24**********************************@microsof t.com... Newbie:
I am writing code to read an xml file. I want two values from the document so I want to save them as I am reading through the elements. I want to
reference them (using Console.WriteLine) after I complete the loop. When I compile I get the "use of unassigned local variable".

What am I doing wrong?

stripped down code:
static void Main()
{
string Msg;

try
{
// Open an XML file
XmlTextReader reader = new XmlTextReader("...");

while ( reader.Read() )
{
if (reader.NodeType == XmlNodeType.Whitespace)
continue;

if (reader.NodeType != XmlNodeType.EndElement )
{
Msg = reader.Value;
}

if (reader.HasAttributes)
{
reader.MoveToFirstAttribute();
}
}
}
catch (Exception e)
{
Console.WriteLine ("Exception: {0}", e.ToString());
}

Console.WriteLine(Msg);
}

[C# Learner]

On Tue, 28 Sep 2004 13:03:09 -0700, Ropo wrote:

What am I doing wrong?

The C# compiler is very strict.

Consider:

1 static void Main() {
2 string message;
3 if (DateTime.Now.Year == 2004) {
4 message = "It's Y2k!";
5 }
6 Console.WriteLine(message);
7 }

If line 6, message isn't *guaranteed* to be assigned, so the compiler will
produce an error.

The fix could be to change line 2 to:

string message = String.Empty;

Now the compiler knows that message definitely *has* been assigned before
the reference to it in line 6, and won't complain any more.

[C# Learner]

On Wed, 29 Sep 2004 06:19:36 +0100, C# Learner wrote:

4 message = "It's Y2k!";

In fact, that should be:

message = "It's Y2k+4!";

Or something like that. :-)

[Ropo]

Excellent info....thanx in bunches.

"C# Learner" wrote:

On Wed, 29 Sep 2004 06:19:36 +0100, C# Learner wrote:

4 message = "It's Y2k!";

In fact, that should be:

message = "It's Y2k+4!";

Or something like that. :-)