Regex pattern matching C#

Question

I want to loop through each file in a folder and save the substring of the file name to a variable.

For example lets say I have the following file in a folder:

ERISRequest_INC1234567.csv //Should Print -> INC1234567

ERISRequest_INC8901234.csv //Should print -> INC8901234

fileName.csv //should skip this one

I want to extract the shown substring if and only if the file name starts with ERISRequest_ and store it in a variable

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

namespace FileName
{
    class Program
    {
        static void Main(string[] args)
        {
            DirectoryInfo di = new DirectoryInfo(@"C:\");
            foreach(FileInfo fi in di.GetFiles())
            {
                Console.WriteLine(fi.Name);

            }
            Console.ReadLine();
        }
    }
}

Answer 1

Get the file name without the extension and then check it starts with your prefix.

using System;
using System.IO;

namespace Quicky
{
    class Program
    {
        static void Main(string[] args)
        {
            const string PREFIX = "ERISRequest_";
            DirectoryInfo di = new DirectoryInfo(@"C:\");
            foreach (FileInfo fi in di.GetFiles())
            {
                if (fi.Name.StartsWith(PREFIX))
                {
                    Console.WriteLine(Path.GetFileNameWithoutExtension(fi.Name).Substring(PREFIX.Length));
                }
            }
        }
    }
}

Answer 2

It helps you. Is that what you're looking for?

    Regex regex = new Regex(@"ERISRequest_(?<val>[a-zA-Z0-9]{1,})");
    DirectoryInfo di = new DirectoryInfo(@"C:\");
    foreach (FileInfo fi in di.GetFiles())
    {
        var match = regex.Match(Path.GetFileNameWithoutExtension(fi.Name));
        if (match.Success)
        {
            Console.WriteLine(match.Groups["val"].Value);
        }
    }
    Console.ReadLine();

Answer 3

EDITED Now, Try this, in C#.

        Regex regex = new Regex(@"ERISRequest_(?<val>[a-zA-Z0-9]{1,})");
        DirectoryInfo di = new DirectoryInfo(@"C:\");
        foreach (FileInfo fi in di.GetFiles())
        {
            var match = regex.Match(Path.GetFileNameWithoutExtension(fi.Name));
            if (match.Success)
            {
                Console.WriteLine(match.Groups["val"].Value);
            }
        }
        Console.ReadLine();