C# - variable reference does not exist in the current context

Question

I have this code in the main window class where I declare some values to put in a ListForTesting list and make the tests appear in a combobox. Later there is another combobox that depends on the first on which I present you the code down bellow:

It may be worth to mention that I am completely new to C#. Only coded in VBA. I'm a mechanical engineer, not software :)

Main Window code

public MainWindow()
{
    InitializeComponent();
    grid_projectConfig.Visibility = Visibility.Collapsed;
    grid_projectOverview.Visibility = Visibility.Collapsed;
    grid_test.Visibility = Visibility.Collapsed;
    grid_reports.Visibility = Visibility.Collapsed;

    //ListForTesting holds the hardcoded set of tests and manoeuvres
    List<HelpClass.TestID> ListForTesting = new List<HelpClass.TestID>();

    //TestObject holds the test name, ID and all the manoeuvres related to it
    HelpClass.TestID TestObject = new HelpClass.TestID();
    TestObject.testName = "Steady State";
    TestObject.ID = 0;
    //Manoeuvre holds the manoeuvre name and its ID
    TestObject.Manoeuvres = new List<HelpClass.ManoeuvresID>();
    HelpClass.ManoeuvresID Manoeuvre = new HelpClass.ManoeuvresID();
    Manoeuvre.manName = "30 kph";
    Manoeuvre.manID = 0;
    //add the Manoeuvre to the TestObject
    TestObject.Manoeuvres.Add(Manoeuvre);
    //create new Manoeuvre
    Manoeuvre = new HelpClass.ManoeuvresID();
    Manoeuvre.manName = "50 kph";
    Manoeuvre.manID = 1;
    TestObject.Manoeuvres.Add(Manoeuvre);
    //add the TestObject to the ListForTesting
    ListForTesting.Add(TestObject);


    //display the tests in a combobox
    combobox_testType.ItemsSource = ListForTesting.Select(t => t.testName);
}

Second combobox code

public void combobox_testType_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    combobox_testType.ItemsSource = ListForTesting[1].Manoeuvres.Select(t => t.manName);
}

this last line of code does not work because it tells me that it does not exist in the current context.

What's the question?

Philippe
– Philippe

2016-05-31 11:00:37 +00:00
Commented May 31, 2016 at 11:00 — Philippe
– Philippe, Commented May 31, 2016 at 11:00

Tommaso Bertoni · Accepted Answer · 2016-05-31 13:28:12Z

3

The problem is the scope of the variable ListForTesting: by declaring it inside your MainWindow constructor you limit its visibility to that method.

To allow to access ListForTesting from another method in your class (i.e.: combobox_testType_SelectionChanged) you have to declare it as a class-level variable like so:

public class MainWindow : Window
{
    private List<HelpClass.TestID> ListForTesting; // Variable declaration

    public MainWindow()
    {
        // code

        ListForTesting = new List<HelpClass.TestID>(); // Initialization

        // code
    }
}

edited May 31, 2016 at 13:28

answered May 31, 2016 at 11:02

Tommaso Bertoni

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Comments

David Pilkington · Accepted Answer · 2016-05-31 11:01:49Z

1

the variable ListForTesting is in the scope of the constructor. You need to move the variable out of there for it to be accessible elsewhere in the class.

List<HelpClass.TestID> ListForTesting;

public MainWindow()
{
...
   ListForTesting = new List<HelpClass.TestID>();
...
}

answered May 31, 2016 at 11:01

David Pilkington

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