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home / developersection / forums / how do you list and filter files using linq?
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How do you list and filter files using LINQ?

Ravi Vishwakarma 446 18 May 2025

How do you list and filter files using LINQ? with example

c# c#linq
Updated 22 May 2025
Ravi Vishwakarma
Ravi Vishwakarma

IT-Hardware & Networking

Ravi Vishwakarma is a dedicated Software Developer with a passion for crafting efficient and innovative solutions. With a keen eye for detail and years of experience, he excels in developing robust software systems that meet client needs. His expertise spans across multiple programming languages and technologies, making him a valuable asset in any software development project.

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1 Answers

Anubhav Sharma
Anubhav Sharma 22 May 2025
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To list and filter files using LINQ, you can combine System.IO with LINQ queries to efficiently query file metadata (like name, size, extension, etc.).

Example: List All Files in a Directory

using System.IO;
using System.Linq;

string folderPath = @"C:\Uploads";

var files = Directory.GetFiles(folderPath)
    .Select(f => new FileInfo(f))
    .ToList();

Filter Examples Using LINQ

1. Filter by Extension

var pdfFiles = files
    .Where(f => f.Extension.Equals(".pdf", StringComparison.OrdinalIgnoreCase))
    .ToList();

2. Filter by File Size (e.g., files > 1 MB)

var largeFiles = files
    .Where(f => f.Length > 1 * 1024 * 1024) // > 1MB
    .ToList();

3. Filter by Creation Date

var recentFiles = files
    .Where(f => f.CreationTime >= DateTime.Today.AddDays(-7)) // last 7 days
    .ToList();

4. Filter by Name Pattern

var matchingFiles = files
    .Where(f => f.Name.Contains("report", StringComparison.OrdinalIgnoreCase))
    .ToList();

5. Combine Filters

var filtered = files
    .Where(f =>
        f.Extension == ".txt" &&
        f.Length < 500_000 &&
        f.CreationTime > DateTime.Today.AddMonths(-1))
    .ToList();

Project to Custom DTO

var fileList = files.Select(f => new
{
    f.Name,
    f.Extension,
    SizeKB = f.Length / 1024,
    Created = f.CreationTime
}).ToList();

Bonus: Recursive File Listing

var allFiles = Directory.GetFiles(folderPath, "*.*", SearchOption.AllDirectories)
    .Select(f => new FileInfo(f))
    .ToList();
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