RegEx -- getting rid of double whitespaces?

Question

I have an app that goes in, replaces "invalid" chars (as defined by my Regex) with a blankspace. I want it so that if there are 2 or more blank spaces in the filename, to trim one. For example:

Deal A & B.txt after my app runs, would be renamed to Deal A   B.txt (3 spaces b/w A and B). What i want is really this: Deal A B.txt (one space between A and B).

I'm trying to determine how to do this--i suppose my app will have to run through all filenames at least once to replace invalid chars and then run through filenames again to get rid of extraneous whitespace.

Can anybody help me with this?
Here is my code currently for replacing the invalid chars:

public partial class CleanNames : Form
{
    public CleanNames()
    {
        InitializeComponent();

    }

    public void Sanitizer(List<string> paths)
    {
        string regPattern = (@"[~#&$!%+{}]+");
        string replacement = " ";

        Regex regExPattern = new Regex(regPattern);


        StreamWriter errors = new StreamWriter(@"S:\Testing\Errors.txt", true);
        var filesCount = new Dictionary<string, int>();


        dataGridView1.Rows.Clear();

           try
            {

              foreach (string files2 in paths)
              {

                string filenameOnly = System.IO.Path.GetFileName(files2);
                string pathOnly = System.IO.Path.GetDirectoryName(files2);
                string sanitizedFileName = regExPattern.Replace(filenameOnly, replacement);
                string sanitized = System.IO.Path.Combine(pathOnly, sanitizedFileName);


                if (!System.IO.File.Exists(sanitized))
                {
                    DataGridViewRow clean = new DataGridViewRow();
                    clean.CreateCells(dataGridView1);
                    clean.Cells[0].Value = pathOnly;
                    clean.Cells[1].Value = filenameOnly;
                    clean.Cells[2].Value = sanitizedFileName;
                    dataGridView1.Rows.Add(clean);

                    System.IO.File.Move(files2, sanitized);
                }

                else
                {
                    if (filesCount.ContainsKey(sanitized))
                    {
                        filesCount[sanitized]++;
                    }
                    else
                    {
                        filesCount.Add(sanitized, 1);
                    }
                    string newFileName = String.Format("{0}{1}{2}",
                    System.IO.Path.GetFileNameWithoutExtension(sanitized),
                    filesCount[sanitized].ToString(),
                    System.IO.Path.GetExtension(sanitized));
                    string newFilePath = System.IO.Path.Combine(System.IO.Path.GetDirectoryName(sanitized), newFileName);
                    System.IO.File.Move(files2, newFilePath);
                    sanitized = newFileName;

                    DataGridViewRow clean = new DataGridViewRow();
                    clean.CreateCells(dataGridView1);
                    clean.Cells[0].Value = pathOnly;
                    clean.Cells[1].Value = filenameOnly;
                    clean.Cells[2].Value = newFileName;

                    dataGridView1.Rows.Add(clean);

                }




              }
            }
           catch (Exception e)
           {
               errors.Write(e);
           }


    }

    private void SanitizeFileNames_Load(object sender, EventArgs e)
    { }

    private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
    {

    }

    private void button1_Click(object sender, EventArgs e)
    {
        Application.Exit();
    }


}

The problem is, that not all files after a rename will have the same amount of blankspaces. As in, i could have Deal A&B.txt which after a rename would become Deal A B.txt (1 space b/w A and B--this is fine). But i will also have files that are like: Deal A & B & C.txt which after a rename is: Deal A   B   C.txt (3 spaces between A,B and C--not acceptable).

Does anybody have any ideas/code for how to accomplish this?

Answer 1

Do the local equivalent of:

s/\s+/ /g;

Answer 2

Just add a space to your regPattern. Any collection of invalid characters and spaces will be replaced with a single space. You may waste a little bit of time replacing a space with a space, but on the other hand you won't need a second string manipulation call.