在ASP.NET中创建动态数据表

Question

I have membership database which contains Roles defined in the role table..Now i want to make datatable to be created dynamically from the the number of roles present in roles table...

here is my code..

DataTable dTable = new DataTable();

string[] rolesarr = Roles.GetAllRoles();
int length = rolesarr.Count();

for (int i = 0; i <= length; i++)
{
     string colname = rolesarr[i];
     if (i == 0)
     {
         dTable.Columns.Add(colname, typeof(string));
     }
     else
     {
         dTable.Columns.Add(colname, typeof(bool));
     }
}

but it is giving error as

"System.IndexOutOfRangeException: Index was outside the bounds of the array."

Any help will be highly appreciated. Thanks in advance..

Answer 1

Change your

i <= length

to

i < length

Because arrays are zero based. Their bounds are 0 to length - 1 .

From Arrays (C# Programming Guide)

Arrays are zero indexed: an array with n elements is indexed from 0 to n-1 .

For example, when you declare an array with 5 elements like;

int[] array = new int[5];

Your elements as indexed from 0 to 4 like;

array[0]
array[1]
array[2]
array[3]
array[4]