ArgumentOutOfRangeException parameter name: Index

Question

I keep getting this 'ArgumentOutOfRange exception non-negative number required, Parameter name: index', whenever I try to open the page and I can't seem to figure out where/how exactly the negative number is appearing. Thank you all in advance!!

var months = data.OrderBy(x => x.ApproximatedStartDate).Select(x => x.Month).Distinct((x, y) => x == y).OrderBy(x => x).ToList();
var upcomingMonths = months.GetRange(months.IndexOf(DateTime.Today.Month), months.Count - months.IndexOf(DateTime.Today.Month));

I'm getting the exception when the code reads the 'upcomingMonths' variable.

stack trace:

[ArgumentOutOfRangeException: Non-negative number required. Parameter name: index]
System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource) +72
System.Collections.Generic.List`1.GetRange(Int32 index, Int32 count) +4951591
InitializeChartBC() 
Page_Load(Object sender, EventArgs e)
System.Web.UI.Control.OnLoad(EventArgs e) +103
System.Web.UI.Control.LoadRecursive() +68
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3811

Why not "Where( Month >= DateTime.Today.Month)" (pseudocode) ? — Fildor
– Fildor, Commented Nov 13, 2017 at 15:42
A minimal reproducible example would be helpful here. It's not really clear what you're trying to achieve, or what data you have. — Jon Skeet
– Jon Skeet, Commented Nov 13, 2017 at 15:43
Well the exception tells you that it is the "index" argument. The stack trace shows that it is the GetRange method of List. Given you only use this once in your quoted code then you can conclude that months.IndexOf(DateTime.Today.Month) must be returning a negative number. The documentation of IndexOf will tell you exactly when that will return a negative number. Job done. Learning to read exception information is a vital skill while programming and one you should definitely take the time to learn. — Chris
– Chris, Commented Nov 13, 2017 at 15:48

Rudresha Parameshappa · Accepted Answer · 2017-11-13 15:43:05Z

3

According to Documentation header of the List

// Exceptions:
//   T:System.ArgumentOutOfRangeException:
//     index is less than 0.-or-count is less than 0.

So I think months doesn't contain Current Month. Before you call the months.GetRange check whether it contains current month and then call the GetRange.

var months = data.OrderBy(x => x.ApproximatedStartDate).Select(x => x.Month).Distinct((x, y) => x == y).OrderBy(x => x).ToList();
 //Anyone corrent me as the list is converted to **.ToList** it wont throw null error I feel
List<T> upcomingMonths = null;  //Where T is the type of the list
if(months.IndexOf(DateTime.Today.Month)>=0)
      upcomingMonths = months.GetRange(months.IndexOf(DateTime.Today.Month), months.Count - months.IndexOf(DateTime.Today.Month));

edited Nov 13, 2017 at 15:43

answered Nov 13, 2017 at 15:38

Rudresha Parameshappa

3,9363 gold badges27 silver badges43 bronze badges

Sign up to request clarification or add additional context in comments.

14 Comments

ProgrammingLlama Over a year ago

Bingo! That's the same conclusion I reached.

Anthony Over a year ago

If it doesn't contain current month, how exactly would I add that into it before calling GetRange?

Fildor Over a year ago

What about using a "Where" instead of "GetRange"?

Anthony Over a year ago

Thank you for the example! I'm not too familiar with checking indexes just yet, how would you go about checking if the index is a negative number, like you said? @john

Rudresha Parameshappa Over a year ago

@Fildor he wants the list starting at index from where the month starts until the end of the list. If the Data is started then he can check month at-least or at-most using where condition

|

Collectives™ on Stack Overflow

ArgumentOutOfRangeException parameter name: Index

1 Answer 1

14 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

14 Comments

Your Answer

Sign up or log in

Post as a guest

Related