CODEWITHSUNDEEP
c#regexlist
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Reputation: 863

Find if an item exists in a list using regex pattern

I've a list of files with timestamp appended to it.I Also have another list which contains regex patterns. I wanted to verify all patterns in 'refFiles' exists in 'files' for not.

Below is the samples files,

List<string> files = new List<string>();
files.Add("AB_DBER_2016101194814.txt");
files.Add("AB_EBER_2016101194815.txt");
files.Add("AB_FBER_2016101194811.txt");

This is the reference patterns:

List<string> refFiles = new List<string>();
refFiles.Add("AB_DBER_[0-9]{13,13}.txt");
refFiles.Add("AB_EBER_[0-9]{13,13}.txt");
refFiles.Add("AB_FBER_[0-9]{13,13}.txt");

I wanted to do something like:

 foreach (var file in refFiles )
 {
   //if file has a match in files then I need to do some code
 }

I wanted to know how I can find the regex pattern in second list to verify that matching patern exists in first list.

Upvotes: 4

Views: 5116

Answers (2)

Shaun Luttin
Shaun Luttin

Reputation: 141542

Here is a general approach, with which you can fiddle here.

Note the change to your regex. It uses \. instead of . inside a literal @ string; that will match a period instead of the wildcard character class.

using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;

public class Program
{
    public static void Main()
    {
        List<string> files = new List<string>();
        files.Add("AB_DBER_2016101194814.txt");
        files.Add("AB_EBER_2016101194815.txt");
        files.Add("AB_FBER_2016101194811.txt");

        // the following will not match
        files.Add("AB_FBER_20161011948111txt");
        files.Add("This_Does_Not_Match.txt");

        List<string> refFiles = new List<string>();
        refFiles.Add(@"AB_DBER_[0-9]{13,13}\.txt");
        refFiles.Add(@"AB_EBER_[0-9]{13,13}\.txt");
        refFiles.Add(@"AB_FBER_[0-9]{13,13}\.txt");
        foreach (var pattern in refFiles)
        {
            var regex = new Regex(pattern);
            foreach (var file in files)
            {
                if (regex.IsMatch(file))
                {
                    Console.WriteLine(file);
                }
            }
        }
    }
}

You can also use LINQ: 

foreach (var file in files)
{
    if (refFiles.Any(pattern => Regex.IsMatch(file, pattern)))
    {
        Console.WriteLine(file);
    }
}

In both cases, this is the output:

AB_DBER_2016101194814.txt
AB_EBER_2016101194815.txt
AB_FBER_2016101194811.txt

Upvotes: 5

tRuEsAtM
tRuEsAtM

Reputation: 3668

This code works for me

        var files = new List<string>
        {
            "AB_DBER_2016101194814.txt",
            "AB_EBER_2016101194815.txt",
            "AB_FBER_2016101194811.txt"
        };

        var refFiles = new List<string>
        {
            "AB_DBER_[0-9]{13,13}.txt",
            "AB_EBER_[0-9]{13,13}.txt",
            "AB_FBER_[0-9]{13,13}.txt"
        };

        foreach (var patternFile in refFiles)
        {
            var regularExp = new Regex(patternFile);
            foreach (var file in files)
            {
                if (regularExp.IsMatch(file))
                {
                    Console.WriteLine(file);
                }
            }
        }

Upvotes: 1

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