Cannot increment integer inside the foreach loop

Question

I have a C# method to convert from a list into an array. The code goes like this:

public String[] ConvertToArray(List<InstallationControl> list)
        {
            String[] Array = null;
            Int32 i = 0;
            foreach (var item in list)
            {
                Array[i] = item.Value.ToString();
                i++;
            }

            return Array;
        }

However, it's always giving me the Null exception. Can someone explain this to me?

You're not initializing your array. String[] Array = new String[list.Count] — Michael, Sep 23 '13 at 16:53
I think you should just use the `ToArray()` method... That or rewrite your loop to something that makes more sense, like a traditional for instead of a foreach with an index variable... Doesn't that just defeat the purpose of using foreach? Plus initialize your array to `list.Count()`. — evanmcdonnal, Sep 23 '13 at 16:56

Michael · Answer 1 · 2013-09-23T17:10:06.320

4

You are not initializing the array you are trying to fill.

String[] Array = new String[list.Count]

Should solve your problem.

This will create an array of [list.Count] strings. You should be aware that each of those strings are null until you them assign a value.

MSDN Arrays

edited Sep 23 '13 at 17:10

answered Sep 23 '13 at 16:54

Michael

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Anirudha · Answer 2 · 2013-09-23T17:12:36.457

1

You need to initialize the array

String[] Array = new String[list.Count];

or simply

String[] Array =list.Select(x=>x.Value.ToString()).ToArray();

edited Sep 23 '13 at 17:12

answered Sep 23 '13 at 16:54

Anirudha

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I guess you meant `list.Select(r=> r.Value.ToString()).ToArray()` – Habib Sep 23 '13 at 17:10

score 0 · Answer 3 · answered Sep 23 '13 at 16:54

0

Change the line to initialize the array

String[] Array = new String[list.Count];

Should work

answered Sep 23 '13 at 16:54

MichaC

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Cannot increment integer inside the foreach loop

3 Answers3