InvalidArgument =值'6'对于索引无效。 参数名称：索引

Question

I created a Listview control with 8 columns. When I need to retrieve text from subitem of Item, I use the following code:

foreach (ListViewItem item in listViewStatus.Items)
            {
                if (item.Tag == f)
                {
                    /* Use locking to synchronise across mutilple thread calls. */
                    lock (_lockObject)
                    {
                        item.SubItems[6].Text = Status;
                    }
                    break;
                }
            }

it shows an exception. But when I replace item.SubItems[6].Text with item.SubItems[5].Text it works. How can I fix this?

Answer 1

SubItems[6]

6它表示列索引而不是行的索引。

Answer 2

显然，SubItems中最多有6列

Answer 3

If you've only created 6, then the values are 0-5; meaning 6 is invalid.

Answer 4

This is a classic "off-by-one" error scenario.

Indicies come in two flavors: Zero-based, and One-based. C# is a zero-based index language. I assume you're either learning a language for the first time, or learning a zero-based language for the first time - Otherwise, I'm missing the point of the question, and I apologize. :)

See Wikipedia, Off-By-One Error: http://en.wikipedia.org/wiki/Off-by-one_error

The ArgumentOutOfRange exception is thrown by the runtime when it realizes that there is no 7th item in the list. This kind of error cannot be caught at compile time (without using heuristics), due to the fact that the list may contain any number of values at any time

TLRD;

Zero-Based (C#):

... = myList[0]; // This is a zero-based indexer.
... = myList[1];
... = myList[2];
... = myList[3];
... = myList[4];
... = myList[5]; // This is the 6th item, although the index is 5.

One-Based (some other language):

... = myList[1]; // This is a one-based indexer.
... = myList[2];
... = myList[3];
... = myList[4];
... = myList[5];
... = myList[6]; // This is the 6th item, and the index is 6.