CODEWITHSUNDEEP
c#arrayslistinterfacepolymorphism
user2102327
user2102327

Reputation: 109

Is there an interface that can be used as a parameter in a method for T[] (an array of type T) and for List<T>

I have two methods that perform the same task: one receiving an array parameter and the a List parameter, both of type string.
Is there a way to replace these two methods by a single method? What type of parameter can replace both?
The methods are:

    public static void NumberLinesInCollection(List<string> list, int startNumberingFromRowNumber = 0)
    {
        int numberOfLines = list.Count;
        for (int i = startNumberingFromRowNumber; i < numberOfLines; i++)
        {
            string sourceString = (i + 1).ToString();
            string resultingString = StringOperations.PadWithBlanks(originalString: (i + 1).ToString(), 
                                                                    fieldLength: numberOfLines.ToString().Length, 
                                                                    position: PaddingDirection.left);
            list[i] = resultingString + ". " + list[i];
        }
    }

and

    public static void NumberLinesInCollection(string[] arrayOfStrings, int startNumberingFromRowNumber = 0)
    {
        int numberOfLines = arrayOfStrings.Length;
        for (int i = startNumberingFromRowNumber; i < numberOfLines; i++)
        {
            string resultingString = StringOperations.PadWithBlanks(originalString: (i + 1).ToString(),
                                                                    fieldLength: numberOfLines.ToString().Length,
                                                                    position: PaddingDirection.left);
            arrayOfStrings[i] = resultingString + ". " + arrayOfStrings[i];
        }
    }

Thank you in advance.

Upvotes: 2

Views: 90

Answers (3)

Hossein Sabziani
Hossein Sabziani

Reputation: 3505

You can use IEnumerable, then it can be either list and array:

public static void NumberLinesInCollection(IEnumerable<string> list, int startNumberingFromRowNumber = 0)
{
}

Upvotes: 1

Heinzi
Heinzi

Reputation: 172478

From the documentation of System.Array:

Single-dimensional arrays implement the IList<T>, ICollection<T>, IEnumerable<T>, IReadOnlyList<T> and IReadOnlyCollection<T> generic interfaces. The implementations are provided to arrays at run time, and as a result, the generic interfaces do not appear in the declaration syntax for the Array class.

From the documentation of List<T>:

Implements ICollection<T>, IEnumerable<T>, IList<T>, IReadOnlyCollection<T>, IReadOnlyList<T>, [and a few non-generic interfaces]

As we can see, there is a nice overlap, allowing you to choose the most fitting interface based on the actual array/list features you require.

In your particular case, IList<T> seems to be most suitable, since it provides both of the following features used in your code:

  • an Item[] indexer and
  • a Count property (inherited from ICollection<T>).

Upvotes: 4

Vivek Nuna
Vivek Nuna

Reputation: 1

you can use IList<string>, this will allow you to pass both List and Array as the parameter while calling the NumberLinesInCollection. array and list both implement IList

Upvotes: 1

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