使用未分配的局部变量错误＃2

Question

I've looked on google and other stackoverflow Use of unassigned local variable errors and I still cannot find the answer. I think that maybe my error is cause be misusing the scopes of ExtractionCtrl. I tried this code to test the scope and it works. So I don't know where is my mistake now.

Testing the scope

namespace RandomTesting
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            int x = 5;

            switch (x)
            {
                case 2:
                    System.Console.WriteLine("Your # is 2");
                    break;

                case 5:
                    System.Console.WriteLine("Your # is :{0}", x);
                    x = x + 2;
                    System.Console.WriteLine("Your # is :{0}", x);
                    break;
            }

            System.Console.WriteLine("Your # is :{0}", x);
            Console.ReadLine();
        }
    }
}

PART OF THE MAIN CODE

switch (arg)
{
    case "AR":
        ExtractionCtrl = new ARExtractionController();

        // add new mapping here
        break;

    case "ICN":
        ExtractionCtrl = new IcnExtractionController();

        // add new mapping here
        break;
}

int ticketID;
if (int.TryParse(arg, out ticketID))
{
    string returnedFilePath = ExtractionController.GetStartupPath();
    ExtractionCtrl.Extract(ticketID, returnedFilePath, AR_TEMPLATE_PATH, MAPPING_PATH);
}

Answer 1

Your switch to set ExtractionCtrl does not have a default-case, so it is possible that ExtractionCtrl is not initalized after the switch. Since you do not show the declaration of ExtractionCtrl, I'm assuming it is declared without initialization:

SomeExtractionCtrlType ExtractionCtrl;

Hence the error.

Answer 2

You most likely need a default block in your switch .

switch (arg)
{
    case "AR":
        ExtractionCtrl = new ARExtractionController();

        // add new mapping here
        break;

    case "ICN":
        ExtractionCtrl = new IcnExtractionController();

        // add new mapping here
        break;
    default:
        ExtractionCtrl = new DefaultExtractionController();
        break;
}

Or you could initialize ExtractionCtrl when you define it. I like the default option more, though.

Answer 3

In Visual Studio, this is a pretty common compile-time error, it means that the compiler thinks there's a chance the variable won't be initialized before it is called. What you should do is add a default case, as other answers say, but also initialize your variable when you declare it, either to null , or to the value you set it to in your default . Visual Studio is unfortunately very picky, and it doesn't see that all potential paths do end up granting a value.