Find exact substring in string array using LINQ in C#

Question

I'm trying to see if an exact substring exists in a string array. It is returning true if the substring exists in the string but it will contains spelling errors.

EDIT: For example if I am checking if 'Connecticut' exists in the string array but it is spelled 'Connecticute' it will still return true but I do not want it to. I want it to return false for 'Connecticute' and return true for 'Connecticut' only

Is there a way to do this using LINQ?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;

namespace ConsoleApplication2
{
class Program
{
    static void Main(string[] args)
    {
        string[] sample = File.ReadAllLines(@"C:\samplefile.txt");
        /* Sample file containing data organised like
        Niall      Gleeson      123 Fake Street     UNIT 63     Connecticute     00703       USA      
         */

        string[] states = File.ReadAllLines(@"C:\states.txt"); //Text file containing list of all US states
        foreach (string s in sample)
        {
            if (states.Any(s.Contains))
            {
                Console.WriteLine("Found State");
                Console.WriteLine(s);
                Console.ReadLine();
            }
            else
            {
                Console.WriteLine("Could not find State");
                Console.WriteLine(s);
                Console.ReadLine();
            }
        }
    }
}
  }

Are you wondering if LINQ has the ability to perform automatic spell-checking? If so, the answer is no. — Joakim Skoog
– Joakim Skoog, Commented May 11, 2017 at 14:18
if there are alternate spellings, you would have to code in the alternatives you would consider to be "passes". this could be done with basic string functions, or with regular expressions. — John Smith
– John Smith, Commented May 11, 2017 at 14:22
@JoakimSkoog I wanted to know if there was a way to return an exact match using .Contains. It appears there isn't. Would you know of a good way to return an exact match? — user3394486
– user3394486, Commented May 11, 2017 at 14:23
if Connecticue should return true for Connecticut, then what about Conecticu and Konnecticut? Your matching rules are totally not clear — Sergey Berezovskiy
– Sergey Berezovskiy, Commented May 11, 2017 at 14:26

Jamiec · Accepted Answer · 2017-05-11 14:44:59Z

6

String.Contains returns true if one part of the string is anywhere within the string being matched.

Hence "Conneticute".Contains("Conneticut") will be true.

If you want exact matches, what you're looking for is String.Equals

...
if (states.Any(s.Equals))
...

answered May 11, 2017 at 14:44

Jamiec

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3 Comments

Mike Chamberlain Over a year ago

But... he doesn't want Conneticute to match Conneticut...?

Jamiec Over a year ago

@MikeChamberlain and "Conetticute".Equals("Connetticut") will not yield true. MInd you, your solution of word boundaries is just a better idea.

Mike Chamberlain Over a year ago

Yeah, the question is a bit ambiguous - hard to know exactly what is being asked.

Mike Chamberlain · Accepted Answer · 2017-05-11 14:55:40Z

4

You could use \b to match word breaking characters (ie. white spaces, periods, start or end of string etc):

  var r = new Regex("\bConneticut\b", RegexOptions.IgnoreCase);
  var m = r.Match("Conneticute");
  Console.WriteLine(m.Success); // false

edited May 11, 2017 at 14:55

answered May 11, 2017 at 14:49

Mike Chamberlain

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2 Comments

user3394486 Over a year ago

Is it possible to pass in the values from a string array into var r? So instead of var r = new Regex("\bConneticut\b", RegexOptions.IgnoreCase); It would be something like var r = new Regex("\bStringArrayValue\b", RegexOptions.IgnoreCase); and it would go through each item in the string array to see if it exists in var m?

Mike Chamberlain Over a year ago

Can't you just loop through your string array, making the same regex comparison for each item?

Pete Kirkham · Accepted Answer · 2017-05-11 14:58:54Z

1

Rather than using string.Contains, which matches whether the string contains the sequence of letters, use a regular expression match, with whatever you consider to be appropriate. For example, this will match on word boundaries,

var x = new [] { "Connect", "Connecticute is a cute place", "Connecticut", "Connecticut is a nice place" };
x.Dump();
var p = new Regex(@"\bConnecticut\b", RegexOptions.Compiled);
x.Where(s=>p.IsMatch(s)).Dump();

This will match "Connecticut" and "CConnecticut is a nice place" but not the other strings. Change the regex to suit your exact requirements.

(.Dump() is used in linqpad, which can be used to experiment with this sort of thing )

answered May 11, 2017 at 14:58

Pete Kirkham

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