Question

What is the difference between test.Rows[0] and test.Rows[test.Rows.Count - 1] if rows is a collection in a datatable.For example
if count =o or count = -1 what will be the situation here

My intention was to determine the last value in that collection.If no value is there in that collection will it make problems
Previously test.Rows[0][“Level”] is always giving 18 digit number but when i made in to test.Rows[test.Rows.Count – 1][“version”] it is giving correct one

SO finally my question is if count = 1 will both statement test.Rows[0] and test.Rows[test.Rows.Count – 1] will be equal or what is the situation will both statement are equal
I debugged code ,if i go with test.Rows[0][“Level”] it always showing one 18 digit constant value,why it is showing like that.This Test is a datatable in .xsd file where i can see one and only ‘Level’ row

Answer 1

In a zero-based collection / array / list, etc; item 0 and item count - 1 are the first and last items respectively.

For example if count =o

If the collection does not have any items, either of the above will usually result in an out-of-range exception. So… don’t do that. Check the size first.

or count = -1

If the count is -1, you have bigger problems – like, you broke the universe

You might also look at LINQ’s FirstOrDefault() / LastOrDefault() etc (both have special checking for typed lists to minimise pain – but I don’t know if .Rows is technically a typed list (IList<T>) – I suspect not); but access via an indexer is convenient and fast.