How to return an array from a function...

Question

0.00/5 (No votes)

See more:

I have created a function that returns a 2 dimensional array...

VB

Public Function Day1ClassBlocks(intSchedID As Integer) As String(,)
...

For Each row In dsResultsTable.Rows
            txtClassBlocks(i, 0) = row("day").ToString()
            txtClassBlocks(i, 1) = row("block").ToString()
            i = i + 1
        Next

        Return txtClassBlocks

This works fine. Then on the page load event I have this code to loop trough and work with it.

VB

<pre>Dim numclasses(,) As String
        Dim intNumOfBlocks As Integer
        Dim i, x As Integer


        numclasses = Day1ClassBlocks(1572)
        
        i = 0


        For each row in numclasses
            Response.Write(">" & numclasses(i, 0).ToString() & " - " & numclasses(i, 1).ToString() & "<br />")
        Next

But when I try to loop through the string array [numclasses] it returns 100 rows when it should only return 10. I can see that the length is 100 but only 10 rows have values. I am very very new to ASP.NET so I am sure I am missing something simple but I have searched and played around with this for 2 days. Also, this is just practice code.

Thanks
-Grajek

What I have tried:

I wrote another function that returns the number of rows and used

VB

For 1 = 0 to intRowCount - 1 Next

which works but I prefer to have just one function for this task.

Posted 1-Feb-17 10:07am

Grajek

Updated 1-Feb-17 10:36am

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Dave Kreskowiak · Answer 1 · 2017-02-01T10:31:00

Solution 1

This has nothing to do with ASP.NET but everything to do with how you treat the returned array.

You enumerating over what you think is a collection of rows in a two dimensional array. That's not how these work.

If you use a ForEach over an array like this, there is no such thing as a row. Each and every element will be returned. So, if you're array is 10 "rows" by 10 "columns" (0 through 9), you will get back 100 "rows".

To treat the array as a 2-dimensional array, you have to use indexers into each dimension of the array:

For i = 0 to numClasses.GetUpperBound(0)
    For j = 0 to numClasses.GetUpperBound(1)
        ...
    Next
Next

Posted 1-Feb-17 10:31am

Dave Kreskowiak

Comments

Grajek 1-Feb-17 17:00pm

Okay, thanks a WHOLE BUNCH. :-) [.GetUpperBound(0)] works perfectly. I knew it was something simple. I am wondering though how the GetUpperBound(0) filters out the "Nothing" "Nothing" elements I see in my watch window and the For Each does not.

Thanks Again For the response.

Grajek

Dave Kreskowiak 1-Feb-17 17:18pm

Filtering? There is no filtering at all.

GetUpperBound only returns a number, the largest index for a dimension of the array. That's it, nothing else.

Grajek 1-Feb-17 17:37pm

How does the [For Each] differ from the [For i = 0 to numClasses.GetUpperBound]? When I use the [For Each] it returns 100 elements regardless of values or no values, but the [For i=0 to numClasses.GetUpperBound(0)] only returns the elements with values other than "Nothing."

Dave Kreskowiak 1-Feb-17 19:14pm

Indexers treat the array as an array and are limited to the bounds of the array in every dimension.

ForEach uses an Enumerator which it gets from the Array.GetEnumerator method on the array. It doesn't see it as an array. To the enumerator the array is just a collection, no dimensions.

Grajek 2-Feb-17 14:12pm

Okay, that makes sense. Thanks!

Like I said very very new to .NET. This helps more than you know!

Thanks again.

Patrice T · Answer 2 · 2017-02-01T10:36:00

By using the debugger, you may discover that the problem is not where you think it is.
I think the problem is in the code you didn't shown.

When you don't understand what your code is doing or why it does what it does, the answer is debugger.
Use the debugger to see what your code is doing. It allow you to execute lines 1 by 1 and to inspect variables as it execute, it is an incredible learning tool.

Debugger - Wikipedia, the free encyclopedia[^]

The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't find bugs, it just help you to. When the code don't do what is expected, you are close to a bug.