IndexOutOfRange Exception C# Multi-Dimensional Array

Question

string[,] Months = new string[12,2] { { "Jan", "1" }, { "Feb", "2" }, { "Mar", "3" }, { "Apr", "4" }, { "May", "5" }, { "Jun", "6" }, { "Jul", "7" }, { "Aug", "8" }, { "Sep", "9" }, { "Oct", "10" }, { "Nov", "11" }, { "Dec", "12" } };

for (int i = 0; i < Months.Length; i++)
{
    if (Convert.ToInt32(Months[i,1]) > DateTime.Now.Month)
    {
        //Do Something
    }
    else
    {
        //Another Task
    }
}

The above code throws an index out of "range exception". However, When I inserted the length of the array manually in the for loop, everything worked

for (int i = 0; i < 12; i++)
{
    if (Convert.ToInt32(Months[i,1]) > DateTime.Now.Month)
    {
        //Do Something
    }
    else
    {
        //Another Task
    }
}

What caused this exception? I have been using similar code for a long time now and no issue. Just wrote this one this morning and faced red screen.

The [Length property](https://msdn.microsoft.com/en-us/library/system.array.length.aspx) returns *the total number of elements in all the dimensions of the Array* — stuartd, Apr 11 '15 at 11:25

score 3 · Answer 1 · answered Apr 11 '15 at 05:49

3

for (int i = Months.GetLowerBound(0); i <= Months.GetUpperBound(0); i++)

answered Apr 11 '15 at 05:49

mathieu

477
3
9

score 2 · Accepted Answer · answered Apr 11 '15 at 05:53

2

for (int i = 0; i < Months.GetLength(0); i++)

Length refers to size of all elements in array, which is 24. To get size of one dimension, use GetLength()

answered Apr 11 '15 at 05:53

Phuong Nguyen

2,870
1
13
22

Thanks @phuongNguyen. I did not know this initially. – codein Apr 12 '15 at 10:48

IndexOutOfRange Exception C# Multi-Dimensional Array

2 Answers2