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c#type-conversion
MoonKnight
MoonKnight

Reputation: 23833

C# List<string[]> to List<object[]> Conversion

All, have I gone mental (this is not the question). I want to convert List<string[]> to List<object[]>

List<string[]> parameters = GetParameters(tmpConn, name);
List<object[]> objParams = parameters.OfType<object[]>();

this is not working, but unless I have forgotten something a conversion using this method should be possible (no Lambdas needed)?

Thanks for your time.

Upvotes: 12

Views: 31338

Answers (4)

Gabe
Gabe

Reputation: 86718

You want to use something like:

List<object[]> objParams = parameters.OfType<object[]>().ToList();

or in C# 4.0, just

List<object[]> objParams = parameters.ToList<object[]>();

or

List<object[]> objParams = parameters.ConvertAll(s => (object[])s);

Upvotes: 22

Ani
Ani

Reputation: 113402

Because of array covariance, in .NET 4.0, you can just do:

// Works because:
// a) In .NET, a string[] is an object[]
// b) In .NET 4.0, an IEnumerable<Derived> is an IEnumerable<Base>              
var result = parameters.ToList<object[]>();

But note that you wouldn't be able to mutate those arrays with anything other than strings (since array covariance isn't truly safe).

If you want truly flexible writable object arrays, you can do:

var result = parameters.Select(array => array.ToArray<object>())
                       .ToList();

(or)

var result = parameters.ConvertAll(array => array.ToArray<object>());

Then you could replace the elements of each inner array with instances of pretty much any type you please.

Upvotes: 4

HatSoft
HatSoft

Reputation: 11201

How about doing it this way

List<string[]> sList = new List<string[]> {new []{"A", "B"}};
List<object[]> oList = sList.Cast<object[]>().ToList();

Upvotes: 0

Amy B
Amy B

Reputation: 110111

OfType<string[]> returns an IEnumerable<string[]>, not a List<object[]>.

Enuemrable.OfType filters out any invalid casts. You may want to consider Enumerable.Cast instead ,which will throw if you make a mistake. If string[] doesn't inherit from object[] (I honestly don't remember), you may need to call Enumerable.Select to provide a conversion.

You definately need a Enumerable.ToList call in there somewhere.

Upvotes: 3

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