How to recursively list all the files in a directory in C#?

Question

How to recursively list all the files in a directory and child directories in C#?

Answer 1

Here is a version of B. Clay Shannon's code not static for excel-files:

class ExcelSearcher
{
    private List _fileNames;

    public ExcelSearcher(List filenames)
    {
        _fileNames = filenames;
    }
    public List GetExcelFiles(string dir, List filenames = null)
    {

        string dirName = dir;
        var dirNames = new List();
        if (filenames != null)
        {
            _fileNames.Concat(filenames);
        }
        try
        {
            foreach (string f in Directory.GetFiles(dirName))
            {
                if (f.ToLower().EndsWith(".xls") || f.ToLower().EndsWith(".xlsx"))
                {
                    _fileNames.Add(f);
                }
            }
            dirNames = Directory.GetDirectories(dirName).ToList();
            foreach (string d in dirNames)
            {
                GetExcelFiles(d, _fileNames);
            }
        }
        catch (Exception ex)
        {
            //Bam
        }
        return _fileNames;
    }