Question

I have log file with around 2000 lines in it. I have gone through first round of formatting. However, I met with difficulty to format my log to what I want for the moment:

Current:

line1: 9/13/2011 3:58:05 AM, abef, 1234, ...
line2: 9/14/2011 3:58:05 AM, adef, 1234, ...
line3:
line4: 9/15/2011 3:58:05 AM, bcdef, 134, ...
line5: 3) sdad
line6: azd
line7: [] asdsdee234 
line2014: 9/16/2011 3:58:05 AM, abcf, 1234, ...

What I want to achieve is to clean up the log to remove lines that do not begin with a date. So line 3, 5, 6 and 7 need to be removed.

Wanted result:

line1: 9/13/2011 3:58:05 AM, abef, 1234, ...
line2: 9/14/2011 3:58:05 AM, adef, 1234, ...
line3: 9/15/2011 3:58:05 AM, bcdef, 134, ...
line2010: 9/16/2011 3:58:05 AM, abcf, 1234, ...

Answer 1

private static IEnumerable<string> ReadOnlyDateTime(string path)
{
    DateTime d;
    string input;
    using (StreamReader stream = new StreamReader(path)) 
    {
        while ((input = stream.ReadLine() != null && DateTime.TryParse(input, out d))
        {
            yield return input;
        }
    }
}

or

DateTime d;
IList<string> = File.ReadLines(path)
                    .Where(line => DateTime.TryParse(line, out d)
                    .ToList();

Then dump result to disk using File.WriteAllLines().