Index was out of range. Must be non-negative and less than the size of the collection


Error is: Index was out of range. Must be non-negative and less than the size of the collection.

Scenario: I have a desktop application which loads XML Files and display the data in Grid. Now, I want to insert another file and want to append the data in both files. But, when I try to merge the data (I mean add the rows to DataTable which has rows of perviously opened file)...I am getting this error.

if (strPreviousFile != "") { dgvBooksDetails.DataSource = dtBooks; int intCurrentRows = dgvBooksDetails.Rows.Count; intBooksCounter = intBooksCounter + intCurrentRows; for (int c = intCurrentRows; c < intBooksCounter; c++) { Book objBook = new Book(); objBook.ID = BookID[c]; objBook.Title = BookTitle[c]; objBook.Author = BookAuthor[c]; objBook.Genre = BookGenre[c]; objBook.Price = Double.Parse(BookPrice[c]); objBook.PublishDate = DateTime.Parse(BookPublish_Date[c]); objBook.Description = BookDescription[c]; dtBooks.Rows.Add(objBook.ID, objBook.Title, objBook.Author, objBook.Genre, objBook.Price, objBook.PublishDate, objBook.Description); } }

How can I overcome this error?


The line causing trouble is this:

int intCurrentRows = dgvBooksDetails.Rows.Count;

You take this value as start for your loop. However, the rows collection counts from 0 to Count-1, so using Count to access a value of the rows collection causes an index out of bounds error.

Another thing: BookTitle, BookAuthor etc. are also indexed from 0 to Count-1 (or Length-1 if they are arrays). I'm not sure from what you've told us, but are you sure that these collections can be accessed by index the way you do? I mean, could it be they only contains the items to be added and thus need to be indexed from 0 to X instead of number of existing items to number of existing items + number of new items (that's what you do in your code)?


Well it seems you have an array <em>n</em> long and you are trying to access the <em>nth</em> or greater element within it. Indexes are <strong>0</strong> based and so an <em>n</em> sized array must be accessed by indexes <em>0</em> to <em>n-1</em>.


Make sure that your arrays (BookTitle, BookAuthor, BookGenre, BookPrice, BookPublish_Date, and BookDescription) have the correct length (minimum intBooksCounter).


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