How do I use LINQ Contains(string[]) instead of Contains(string)


I got one big question.

I got a linq query to put it simply looks like this:

from xx in table
where xx.uid.ToString().Contains(string[])
select xx

The values of the string[] array would be numbers like (1,45,20,10,etc...)

the Default for .Contains is .Contains(string).

I need it to do this instead: .Contains(string[])...

EDIT : One user suggested writing an extension class for string[]. I would like to learn how, but any one willing to point me in the right direction?

EDIT : The uid would also be a number. That's why it is converted to a string.

Help anyone?

12/2/2011 6:46:53 PM

Accepted Answer

spoulson has it nearly right, but you need to create a List<string> from string[] first. Actually a List<int> would be better if uid is also int. List<T> supports Contains(). Doing uid.ToString().Contains(string[]) would imply that the uid as a string contains all of the values of the array as a substring??? Even if you did write the extension method the sense of it would be wrong.


Unless you changed it around and wrote it for string[] as Mitch Wheat demonstrates, then you'd just be able to skip the conversion step.


Here is what you want, if you don't do the extension method (unless you already have the collection of potential uids as ints -- then just use List<int>() instead). This uses the chained method syntax, which I think is cleaner, and does the conversion to int to ensure that the query can be used with more providers.

var uids = arrayofuids.Select(id => int.Parse(id)).ToList();

var selected = table.Where(t => uids.Contains(t.uid));
2/4/2015 5:35:04 AM

If you are truly looking to replicate Contains, but for an array, here is an extension method and sample code for usage:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ContainsAnyThingy
    class Program
        static void Main(string[] args)
            string testValue = "123345789";

            //will print true
            Console.WriteLine(testValue.ContainsAny("123", "987", "554")); 

            //but so will this also print true
            Console.WriteLine(testValue.ContainsAny("1", "987", "554"));


    public static class StringExtensions
        public static bool ContainsAny(this string str, params string[] values)
            if (!string.IsNullOrEmpty(str) || values.Length > 0)
                foreach (string value in values)
                        return true;

            return false;

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