ASP.Net c# adding items to jagged array

Question

im trying to add items to jagged array's, the data is being pulled from a datarowview, i have the following code

foreach (DataRowView answer in AnswersInQuestion)
{
    answersJArray[index] = new string[noOfAnswersInQuestion];
    answersJArray[index][j] = answer["ChoiceText"].ToString();
    j++;
}

the first item gets added in fine, but when the 2nd item is put in the first item is set to null again. so for example the first time round this is what the array will look like

arr[0][0] = answer 1
arr[0][1] = null
arr[0][2] = null
arr[0][3] = null

and the 2nd time round the array will look like

arr[0][0] = null
arr[0][1] = answer 2
arr[0][2] = null
arr[0][3] = null

can any one help me on this !!

thanks

tzenes · Accepted Answer · 2010-02-23 17:54:03Z

2

Your constructor is being called each time (hence the first item being set to null). Put your string array constructor outside of your for-each loop (perhaps in its own loop.

answered Feb 23, 2010 at 17:54

tzenes

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Comments

AaronLS · Accepted Answer · 2010-02-23 17:55:12Z

1

You need a nested loop, because you are creating a brand new array each time and blowing the old one away.

//souround with a loop that increments index whenever you want to create a new group of questions
    answersJArray[index] = new string[noOfAnswersInQuestion];
    foreach (DataRowView answer in AnswersInQuestion)
    {

        answersJArray[index][j] = answer["ChoiceText"].ToString();
        j++;
    }

answered Feb 23, 2010 at 17:55

AaronLS

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2 Comments

AaronLS Over a year ago

Wow I think Spencer revenge downvoted me because he didn't like my comment pointing out his error. Then he deleted his post in embarrasment. Guess he took his ball and went home :)

JonH Over a year ago

+1 to negate a downvote you didnt deserve :). Happens to me all the time.

Joel Etherton · Accepted Answer · 2010-02-23 17:55:30Z

1

What is index? You don't seem to be incrementing it, and each time through your foreach you're creating a new one and dumping it into the same index. Basically rewriting it each time.

You might find more use in using a List to accomplish this jagged array. It will make adding/removing a little easier, and it might help a touch in enumerating.

answered Feb 23, 2010 at 17:55

Joel Etherton

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Comments

marts · Accepted Answer · 2012-01-01 16:09:14Z

0

My approach is to create a hashset of string arrays then populate at will, and at the end, convert ToArray()

e.g.

HashSet<string[]> data = new HashSet<string[]>();

data.Add(new string[] { "mode", "create" });
data.Add(new string[] { "title", this.TextBoxCreateTitle.Text });

data.ToArray();      // our jagged array

edited Jan 1, 2012 at 16:09

user212218

answered Apr 14, 2011 at 18:48

marts

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