IndexOutOfRangeException when trying to access array element

Question

I can't figure out why I'm getting the out of range exception on the following piece of code. The values for _maxRowIndex and _maxColIndex are 5, and 0 respectively. The exception is being thrown on the first time through when row and col are both equal to 0. I don't understand why 0, 0 would be out of bounds on the array.

    _cells = new ToolBarButton[_maxRowIndex, _maxColIndex];
    .
    .
    .
    for (int col = 0; col <= _maxColIndex; col++) {
                    for (int row = 0; row <= _maxRowIndex;  row++)
                    {

                      if (_cells[row, col] == null)
                        {
                           PopulateCell(toolBarbutton, row, col);
                        }

                    }
                }

Mamta D · Accepted Answer · 2010-11-23 03:50:33Z

4

Array indices start from 0 and are upto [upperbound-1]. Since your loop starts at 0, it must end at < the limit value rather than <= limit value. So, change the "<=" to "<" in the loop. Eg:

col <= _maxColIndex

should be changed to

col < _maxColIndex

answered Nov 23, 2010 at 3:50

Mamta D

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Comments

jtdubs · Accepted Answer · 2010-11-23 03:50:35Z

1

If you want the max index to be 5, that means the array needs to be of length 6 as the first element is at index 0.

So, change:

_cells = new ToolBarButton[_maxRowIndex, _maxColIndex];

to:

_cells = new ToolBarButton[_maxRowIndex+1, _maxColIndex+1];

answered Nov 23, 2010 at 3:50

jtdubs

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2 Comments

jtdubs Over a year ago

Or, do what Mamta suggested. It depends on whether you want there to be 5 items in your list, or the last item to be at index 5.

poke Over a year ago

I want the last index to be 5 for a total of 6 items in the list. I didn't occur to me that the declaration was for total elements, not highest index. I made the change that you suggested and it works the way I want it to now.

Tim Joseph · Accepted Answer · 2010-11-23 03:51:28Z

1

You have <= in your for statement...

So your loop evaluates for col =0, 1, 2, 3, 4 and 5... 5 is out of bounds

answered Nov 23, 2010 at 3:51

Tim Joseph

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Comments

gangakinarewala · Accepted Answer · 2012-01-20 16:09:57Z

1

I guess you should declare _cells as below

_cells = new ToolBarButton[5,1];

instead of

_cells = new ToolBarButton[5,0];

edited Jan 20, 2012 at 16:09

user212218

answered Nov 23, 2010 at 3:51

gangakinarewala

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