Object reference not set to an instance of an object error c#

Hi Expert,

I am a beginner in visual c#, i have a problem while running this code string

Code:

---

namespace sampleprocess
{
    public partial class main : Form
    {
        public main()
        {
            InitializeComponent();

        }

        private string[] betPosCol;

private unsafe void setArrays()
{

        betPosCol[1] = "Red";
        betPosCol[2] = "Black";
        betPosCol[3] = "Red";
        betPosCol[4] = "Black";
        betPosCol[5] = "Red";
}
}
}

---

the troubleshooter said that : use "new" keyword to create an object instance

Please help me what is wrong with my code

Regards,

this is the vb.net forum, the c# forum is at http://www.vbforums.com/forumdisplay.php?30-C

you're trying to use elements in an un dimensioned array.

Next time just report your thread and ask that it be moved... now you have duplicate posts...
http://www.vbforums.com/showthread.p...object-error-c

The mods have been alerted to it, and will probably merge them at some point.

mean while... while you have declared an array, you haven't specified how big the array is to be... it's not initialized.

all this does:
private string[] betPosCol;

is to tell C# "Hey, I need a box"....

you never created the box.

Code:

---

betPosCol = new string[]; // while I think you can get away with that, it's a good idea to specify the size of the array if you can...

---

c# Code:

{
 
            betPosCol = new string[5]; // gives you elements 0-4...
 
            betPosCol[0] = "Red";
            betPosCol[1] = "Black";
            betPosCol[2] = "Red";
            betPosCol[3] = "Black";
            betPosCol[4] = "Red";
        }

-tg

When you have something like this:

Code:

---

private string[] betPosCol;

---

The error is here when you try to assign elements to the incidies.

Code:

---

betPosCol[1] = "Red";
betPosCol[2] = "Black";
betPosCol[3] = "Red";
betPosCol[4] = "Black";
betPosCol[5] = "Red";

---

You need to somehow show how much space you want to allocate on the heap (unless you're using stackalloc here which isn't the case), for the number of elements of that type you will be holding in the array. *Note: I'll assume 5 since you only have 5 strings.

csharp Code:

private string[] betPosCol = new string[5];

This is wrong though too:

Code:

---

betPosCol[1] = "Red";

---

Not syntax-wise, but arrays are based on a 0-based indexing system. First index you should be assigning should be 0, not 1. This means that since you have 5 strings, the last index should be 4 for the last element in the array, and you should be assigning indexes [0], [1], [2], [3], [4]. (Not 1, 2, 3, 4, 5).

Cheers :)
Ace

Thanks for the report tg.....Duplicate threads merged