CODEWITHSUNDEEP
c#.netvisual-studio-2010classvariables
Nisse
Nisse

Reputation: 47

How to use variables from another class

Alright, here we go. I am kinda new with programming and C#, but I'm learning it with John Sharp's Visual C#: Step By Step book. (I wonder if that dude's last name is really Sharp)

Anyway, I'm trying to create an application that will help me transpose note. It's a windows forms app and I'm using two classes: form1.cs where all the code happens and vars.cs where all the variables are stored.

My problem is that I want to use string vars.noteChosen and define with comboBoxNote's currently selected item (e.g. C). Whenever I do this, however, when I execute vars.noteChosen = comboNote.SelectedText; I get a "Object reference not set to an instance of an object." error. Any ideas? (comboNote is a combobox)

This is vars.cs

namespace Transposer
{
    class vars
    {
        public static bool rbTransposeUp = true;
        public static string noteChosen = ""; //
        public static string toTranspose = ""; // 
        public static int note = 0;
        public static string boxResultText = note.ToString();
    }
}

and this is a part of form1.cs

namespace Transposer
{
    public partial class Transposer : Form
    {
        public Transposer()
        {
            vars.noteChosen = comboNote.SelectedText;
            vars.toTranspose = comboNote.Text;
            InitializeComponent();
        }

...

What am I doing wrong?

Upvotes: 2

Views: 151

Answers (1)

Andrew Jones
Andrew Jones

Reputation: 1001

Move the lines after the call to InitializeComponent(); It's this call that is creating the comboNote object.

That is

    public Transposer()
    {
        InitializeComponent(); // this constructs the comboNote
        vars.noteChosen = comboNote.SelectedText;
        vars.toTranspose = comboNote.Text;
    }

Upvotes: 6

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