Question

I have been given some file name which can be like

<filename>YYYYMMDD<fileextension>

some valid file names that will satisfy the above pattern are as under

xxx20100326.xls, 
xxx2v20100326.csv, 
x_20100326.xls,
xy2z_abc_20100326_xyz.csv,
abc.xyz.20100326.doc,
ab2.v.20100326.doc,
abc.v.20100326_xyz.xls

In what ever be the above defined case, I need to pick up the dates only. So for all the cases, the output will be 20100326.

I am trying to achieve the same but no luck.

Here is what I have done so far

string testdata = "x2v20100326.csv";

string strYYYY = @"\d{4}";
string strMM = @"(1[0-2]|0[1-9])";
string strDD = @"(3[0-1]|[1-2][0-9]|0[1-9])";           
string regExPattern = @"\A" +  strYYYY + strMM + strDD +  @"\Z";
Regex regex = new Regex(regExPattern);
Match match = regex.Match(testdata);
if (match.Success)
{
  string result = match.Groups[0].Value;
} 

I am using c#3.0 and dotnet framework 3.5

Please help. It is very urgent

Thanks in advance.

Answer 1

Characters \A and \Z – begin and end of the string respectivly.
I think you need pattern like:

string regExPattern = @"\A.*(?<FullDate>" +  strYYYY + strMM + strDD +  @").*\..*\Z";

“.*” – any symbols at the begin
“.*\..*” – any symbols before the dot, dot and any symbols after dot

And get a full date:

match.Groups["FullDate"]