I want to use `[]` to check if a string exists in an array or not

Question

Currently my code is like that

public class ExampleClass
{
    private static string[] words = new string[] { "Word1","Word2","Word3","Word4","Word5" };

    public static bool IsExist(string Word)
    {
        return words.Any(w => w == Word);
    }
}

And am calling that as

ExampleClass.IsExist("Word1"); //Returns true
ExampleClass.IsExist("WordNotExist"); //Returns false

But i want to call like this

ExampleClass.IsExist["Word1"]; //Returns true
ExampleClass.IsExist["WordNotExist"]; //Returns false

How should i modify my class to do so please help me out

I see no reason for that, and you cannot declare an indexed property in static class. — Alessandro D'Andria, Aug 25 '16 at 09:29
no problem my code is compleately diffrent. please give me any idea what i have to do to accomplish this — Nitesh Shaw, Aug 25 '16 at 09:30

score 4 · Accepted Answer · answered Aug 25 '16 at 09:32

I think you are going really bad here since using an indexer to call a method is just wrong. And with that, you can't have indexers on static classes.

That said, this is how it does work:

public class ExampleClass
{
    public class IsExistHelper
    {
        private static string[] words = new string[] { "Word1", "Word2", "Word3", "Word4", "Word5" };

        public bool this[string Word]
        {
            get
            {
                return words.Any(w => w == Word);
            }
        }
    }

    public static IsExistHelper IsExist { get; } = new IsExistHelper();
}

I have used an inner class to create a helper, which creates your property name. Inside there is an indexer that has your original code.

score 1 · Answer 2 · answered Aug 25 '16 at 09:32

Not sure why you would want to do it that way, but:

public class ExampleClass
{
    private string[] words = new string[] { "Word1", "Word2", "Word3", "Word4", "Word5" };

    public bool this[string Word]
    {
        get { return words.Any(w => w == Word); }
    }
}

It must be called with an instance:

var _ = new ExampleClass();
var isTrue = _["Word1"] == true

Unfortunately you cannot do it with a static member. Alternatively you need to create an indexer inside an auxillary class that's instance name is IsExist.

My opinion is that you should leave it as it is.

Gilad Green · Answer 3 · 2016-08-25T09:46:17.363

To achieve it exactly the way you want it (even though in my opinion it isn't a good design) use an inner class that will override the [] operator and will check your condition. Then in your original class have a property of that inner class.

Keep in mind that when overriding the [] operator you can't be using a static class.

See that instead of using Any you can just use Contains - because you are checking for the entire object itself it is a cleaner way to do so

public static class ExampleClass
{

    public class InnerIsExist
    {
        private string[] words = new string[] { "Word1", "Word2", "Word3", "Word4", "Word5" };

        public bool this[string word]
        {
            get {  return words.Contains(word); }
        }
    }

    public static InnerIsExist IsExist { get; } = new IsExistClass();
}

Use:

var doesItContain = ExampleClass.IsExist["b"]; // false

score 1 · Answer 4 · edited May 23 '17 at 10:31

1

Currently, you are calling a function and its as simple as declaring it, but for square brackets, you will have to overload them. Here is a helpful link: How do I overload the square-bracket operator in C#?

Basically, in your case it should look like this:

public bool this[string Word]
{
    get { return words.Any(w => w==Word); }
}

I haven't tested the code, so let me know if it works.

edited May 23 '17 at 10:31

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answered Aug 25 '16 at 09:39

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I want to use `[]` to check if a string exists in an array or not

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