Sort files, size

Each file in a directory has a size in bytes. A C# method can sort an array of these files by their sizes in bytes—from largest to smallest (or the opposite).

This logic is sometimes useful for categorization and presenting file lists. Many approaches are possible, but we use the LINQ extension methods.

Example

We use the FileInfo class and its Length property to get the length of each file. The File class doesn't have a Length getter, and reading in the entire file each time would be wasteful.

using System;
using System.IO;
using System.Linq;

// Step 1: get file names with GetFiles.
const string dir = "programs/";
string[] files = Directory.GetFiles(dir);

// Step 2: order by size.
var sorted = from f in files
             orderby new FileInfo(f).Length descending
             select f;

// Step 3: list files.
foreach (string name in sorted)
{
    Console.WriteLine(name);
}
programs/words.txt
programs/search-perls.txt
...

Notes, LINQ

In the C# language, using the LINQ extensions is often the easiest and simplest way to sort things. It is easy to sort with a computed value like the FileInfo Length.

In complex applications, we can store the file metadata in object models. But not all applications are complex and this code is useful for small tasks.