string[,] does not contain a definition for 'Contains'

Question

I have a function that checks if a 2-dimensional string array contains a specific string value using .Contains. System.Linq is being used, as seems to be the problem in similar questions, however I still get the error of:

'string[,]' does not contain a definition for 'Contains' and the best extension method overload 'Queryable.Contains(IQueryable,string)' requires a receiver of type 'IQueryable'.

This error persists no matter what I change the comparison value to. The context for the error occuremce is as

string comparisonString = " "; 
bool victoryRequirement = mineArray.Contains(comparisonString);

I hope someone can tell me why this error occurs and whether or not I am able to use Contains for this purpose. I suspect the 2-dimensional array is partly at fault, but I am not that experienced.

2D array is not the same as an array of arrays. LINQ is for 1-d arrays. — Sergey Kalinichenko, Sep 25 '16 at 14:18
Is there a workaround or similar way to compare all values for a 2d array, as I must a 2d array for my purpose — Marc, Sep 25 '16 at 14:21
Try writing your own extension method. Most of LINQ query methods (including `Contains`) are extension methods. — Farhan Nasim, Sep 25 '16 at 14:30
may be helpful to you : http://stackoverflow.com/questions/12344002/string-does-not-contain-a-definition-for-contains — Sunil Kumar, Sep 25 '16 at 14:53

Eric Lippert · Answer 1 · 2016-09-25T16:38:40.487

Though the answer of Adil Mammodov appears to work, it is not very general. I would have preferred to write this as the much shorter and more flexible:

public static IEnumerable<T> ToSequence<T>(this T[,] items)
{
  return items.Cast<T>();
}

And now you can simply use ToSequence to turn an array into a sequence, and then apply a sequence operator to it.

myItems.ToSequence().Contains(target);

Also, while we're looking at your code: try to name things according to what they do, not what type they are. If you have "Array" and "String" in names of things, they could have better, more descriptive names. The type is already annotated in the type.

It is possible to generalize my method by implementing generics, but this is way better and deserves to be accepted answer. — Adil Mammadov, Sep 25 '16 at 15:00

score 2 · Accepted Answer · edited Sep 29 '17 at 16:47

You can write your own contains method for two dimensional string array like below:

public bool TwoDimensionalContains(string[,] inputArray, string comparisonString)
{            
    for (int i = 0; i < inputArray.GetLength(0); i++)
    {
        for (int j = 0; j < inputArray.GetLength(1); j++)
        {                    
            // If matching element found, return true
            if (comparisonString.Equals(inputArray[i, j]))
                return true;
        }
    }
    // No matchincg element found, return false
    return false;
}

Then use it as below:

string[,] myArray = new string[2, 2]
{
    { "One", "Two" },
    {  "Three", "Four" }
};

bool contains = TwoDimensionalContains(myArray, "Three");

You can also make TwoDimensionalContains method, extension method to use it as other Linq methods.

LoztInSpace · Answer 3 · 2016-09-25T15:07:36.583

1

Actually this works:

var c=myArray.Cast<string>().Select(x=>x).Contains("Three");

even easier:

var c=myArray.Cast<string>().Contains("Three");

edited Sep 25 '16 at 15:07

answered Sep 25 '16 at 15:02

LoztInSpace

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This is similar to @EricLipert's answer and `Select` is redundant here – Adil Mammadov Sep 25 '16 at 15:04
Hah - yes so it is. I came about it from a roundabout way :) – LoztInSpace Sep 25 '16 at 15:06

string[*,*] does not contain a definition for 'Contains'

3 Answers3

string[,] does not contain a definition for 'Contains'