The variable 'MyException' is declared but never used

Question

I need to clear this warning :

try
{
    doSomething()
}
catch (AmbiguousMatchException MyException)
{
    doSomethingElse()
}

The complier is telling me :

The variable 'MyException' is declared but never used

How can I fix this.

score 157 · Accepted Answer · edited Aug 29 '17 at 06:47

157

You can remove it like this:

try
{
    doSomething()
}
catch (AmbiguousMatchException)
{
    doSomethingElse()
}

Use warning disable like this:

try
{
    doSomething()
}
#pragma warning disable 0168
catch (AmbiguousMatchException exception)
#pragma warning restore 0168
{
    doSomethingElse()
}

Other familiar warning disable

#pragma warning disable 0168 // variable declared but not used.
#pragma warning disable 0219 // variable assigned but not used.
#pragma warning disable 0414 // private field assigned but not used.

edited Aug 29 '17 at 06:47

Gilad Green

36,708
7
61
95

answered Jun 23 '11 at 14:27

Jalal Said

15,906
7
45
68

4

A list of all compiler errors and warnings are available at the [MSDN](http://msdn.microsoft.com/en-US/library/ms228296(v=VS.80).aspx) – Jalal Said Jun 23 '11 at 16:38
The solution given by @fparadis2 is better since not advisable to supress warnings when we can fix it – Ram May 17 '13 at 12:34
@dasariramacharanprasad that was my first suggestion, re-read my answer ;) – Jalal Said May 20 '13 at 11:21
solution #2 is not a solution, it is a mask. – Gusdor Mar 03 '14 at 10:19
But it is a sharp one isn't it :) – Jalal Said Mar 04 '14 at 10:19
#2 is useful when you want to look at the exception in the debugger or use it in debug only code. (Yes, I realize that #if DEBUG blocks introduce a code smell of their own.) – Eric Hirst Jul 07 '21 at 22:33

score 43 · Answer 2 · answered Jun 23 '11 at 14:27

43

You declare a name for the exception, MyException, but you never do anything with it. Since it's not used, the compiler points it out.

You can simply remove the name.

catch(AmbiguousMatchException)
{
   doSomethingElse();
}

answered Jun 23 '11 at 14:27

Khepri

9,547
5
45
61

score 29 · Answer 3 · answered Jun 23 '11 at 14:28

29

You can simply write:

catch (AmbiguousMatchException)

and omit the exception name if you won't be using it in the catch clause.

answered Jun 23 '11 at 14:28

fparadis2

913
7
12

+1 since it resolves the warning! not explained in [MSDN](http://msdn.microsoft.com/query/dev10.query?appId=Dev10IDEF1&l=EN-US&k=k(RETHROWTOPRESERVESTACKDETAILS);k(TargetFrameworkMoniker-%22.NETFRAMEWORK%2cVERSION%3dV4.0%22);k(DevLang-CSHARP)&rd=true). – Ram May 17 '13 at 12:33

score 3 · Answer 4 · answered Jun 23 '11 at 15:04

3

You could write the exception out to a log if you've got one running. Might be useful for tracking down any problems.

Log.Write("AmbiguousMatchException: {0}", MyException.Message);

answered Jun 23 '11 at 15:04

Neil

5,179
8
48
87

score 2 · Answer 5 · answered Jun 23 '11 at 14:28

2

The trouble is, you aren't using your variable MyException anywhere. It gets declared, but isn't used. This isn't a problem... just the compiler giving you a hint in case you intended to use it.

answered Jun 23 '11 at 14:28

Brad

159,648
54
349
530

score 1 · Answer 6 · answered Oct 08 '18 at 18:42

1

but never used means that you should use it after catch() such as writing its value to console, then this warning message will disappear.

catch (AmbiguousMatchException MyException)
{
    Console.WriteLine(MyException); // use it here
}

answered Oct 08 '18 at 18:42

Ray Chakrit

404
5
7

score 0 · Answer 7 · answered Mar 10 '23 at 15:15

0

Just ran into this, where the exception was used based upon compiler variables...

Anyway, my solution was:

 _ = MyException;

Picks it up as used, acknowledges that it isn't really being used.

answered Mar 10 '23 at 15:15

jmoreno

12,752
4
60
91

The variable 'MyException' is declared but never used

7 Answers7

Linked

Related