Delete files older than 3 months old in a directory using .NET

Question

I would like to know (using C#) how I can delete files in a certain directory older than 3 months, but I guess the date period could be flexible.

Just to be clear:

Answer 1

since the solutions with new FileInfo(filePath) are not easily testable, I suggest to use Wrappers for classes like Directory, File and Path like this:

public interface IDirectory
{
    string[] GetFiles(string path);
}

public sealed class DirectoryWrapper : IDirectory
{
    public string[] GetFiles(string path) => Directory.GetFiles(path);
}

public interface IFile
{
    void Delete(string path);
    DateTime GetLastAccessTime(string path);
}

public sealed class FileWrapper : IFile
{
    public void Delete(string path) => File.Delete(path);
    public DateTime GetLastAccessTimeUtc(string path) => File.GetLastAccessTimeUtc(path);
}

Then use something like this:

public sealed class FooBar
{
    public FooBar(IFile file, IDirectory directory)
    {
        File = file;
        Directory = directory;
    }

    private IFile File { get; }
    private IDirectory Directory { get; }

    public void DeleteFilesBeforeTimestamp(string path, DateTime timestamp)
    {
        if(!Directory.Exists(path))
            throw new DirectoryNotFoundException($"The path {path} was not found.");

        var files = Directory
            .GetFiles(path)
            .Select(p => new
            {
                Path = p,
                // or File.GetLastWriteTime() or File.GetCreationTime() as needed
                LastAccessTimeUtc = File.GetLastAccessTimeUtc(p) 
            })
            .Where(p => p.LastAccessTimeUtc < timestamp);

        foreach(var file in files)
        {
            File.Delete(file.Path);
        }
    }
}