Cannot convert arraylist to string array

Question

    public string[] getallTourID()
    {
        ArrayList TourIDs = new ArrayList();
        foreach (Tour o in TourCollections) //TourCollections is an arraylist of tour objects
        {
            TourIDs.Add(o.getID); //ID is a string from the tour object
        }
        return TourIDs.ToArray(typeof(string));
    }

Hi, I needed help with this issue where I cannot convert the arraylist to string array. The error says that:

Cannot implicitly convert type System.Array to string[], an explicit conversion exist

The problem comes from the ToArray() function. May I know what is the issue?

Will really appreciate the help :)

Aria · Accepted Answer · 2017-12-30 11:32:24Z

2

Try this:

Solution 1:

string[] array = TourIDs.ToArray(typeof(string)) as string[];

Solution 2:

String[] array= (String[])TourIDs.ToArray(typeof(string));

answered Dec 30, 2017 at 11:32

Aria

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8 Comments

Aria Over a year ago

Then why down vote ?, there is many ways to cast that list to string array but I have posted what he want as his snippet code, Down vote with no reason because it accepted as answer ?!!!

Aria Over a year ago

Please let me know why ?

Pac0 Over a year ago

downvotes occur because people think it is not the best way to solve OP's problem. (btw, I didn't downvote your answer)

Salah Akbari Over a year ago

This may not the best way to solve the OP's problem, but it is valid answer and it is not deserved for downvote. Downvotes are for incorrect answers and really bad tries!

Pac0 Over a year ago

@Aria I don't think your answer deserves any downvote either, but at the end it's just the opinion of members who see the question and its answers.

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Ousmane D. · Accepted Answer · 2017-12-30 11:42:45Z

2

I don't see why you need a raw ArrayList collection, you should be making it a List<Tour> and then extract the Id's:

as such:

return TourCollections.Select(t => t.getId).ToArray();

if for some reason you cannot do that then use OfType to only return objects from a source collection that are of a certain type.

return TourIDs.OfType<string>().ToArray();

edited Dec 30, 2017 at 11:42

answered Dec 30, 2017 at 11:31

Ousmane D.

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Comments

Pac0 · Accepted Answer · 2017-12-30 12:02:39Z

1

To solve what you want, you can simply use a simple linq query and avoid any intermediate explicit array / list :

using System.Linq;

public string[] getallTourID()
{
    return TourCollections.Select(o => o.getId).ToArray();
}

You could actually do litteraly what you want by casting the result of ToArray(typeof(string)) as string[], but the usual modern "Csharpic" way to do it is the linq projection.

edited Dec 30, 2017 at 12:02

answered Dec 30, 2017 at 11:32

Pac0

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Comments

Irf92 · Accepted Answer · 2017-12-30 11:34:05Z

0

Use the following code

  TourIDs.ToArray(typeof(string)) as string[];

For further info, Refer https://www.dotnetperls.com/convert-arraylist-array

answered Dec 30, 2017 at 11:34

Irf92

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