C#

string sFile = System.IO.File.ReadAllText(@"c:\test.txt");
string sRegEx = @"(\.[0-9][0-9][0-9][0-9])";

foreach (Match oMatch in Regex.Matches(sFile, sRegEx)) {
  sFile = sFile.Replace(oMatch.Value.ToString(), ".0000");
}
System.IO.File.WriteAllText(@"c:\test.txt", sFile);

d@nish wrote:

string sRegEx = @"(\.[0-9][0-9][0-9][0-9])";

string sRegEx = @"(\.[0-9]{4})";

string sFile = System.IO.File.ReadAllText(@"c:\test.txt");
Regex r = new Regex(@"(\.[0-9][0-9][0-9][0-9])");
sFile = r.Replace(sFile, ".0000");
System.IO.File.WriteAllText(@"c:\test.txt", sFile);

Regex regex = new Regex(
    @"(((?<Start>-?)(?<Part>\d*))(\.\d{4}))",
    RegexOptions.IgnoreCase
    | RegexOptions.Multiline
    | RegexOptions.IgnorePatternWhitespace
    | RegexOptions.Compiled
    );

${Start}${Part}.0000

Pete O'Hanlon wrote:

Regex regex = new Regex( @"(((?-?)(?\d*))(\.\d{4}))", RegexOptions.IgnoreCase | RegexOptions.Multiline | RegexOptions.IgnorePatternWhitespace | RegexOptions.Compiled );