Question

I have these strings as a response from a FTP server:

1. 02-17-11 01:39PM <DIR> dec

2. 04-06-11 11:17AM <DIR> Feb 2011

3. 05-10-11 07:09PM 87588 output.xlsx

4. 06-10-11 02:52PM 3462 output.xlsx

where the pattern is: [datetime] [length or <dir>] [filename]

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Edit: my code was- @"^\d{2}-\d{2}-\d{2}(\s)+(<DIR>|(\d)+)+(\s)+(.*)+"

I need to parse these strings in this object:

class Files{

Datetime modifiedTime,
bool ifTrueThenFile,
string name

}

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Please note that, filename may have spaces.

I am not good at regex matching, can you help?

Answer 1

Regex method

One approach is using this regex

@"(\d{2}-\d{2}-\d{2} \d{2}:\d{2}(?:PM|AM)) (<DIR>|\d+) (.+)";

I am capturing groups, so

// Group 1 - Matches the DateTime
(\d{2}-\d{2}-\d{2} \d{2}:\d{2}(?:PM|AM))

Notice the syntax (?:xx), it means that the content here will not be caught in a group, we need to match PM or AM but this group alone doesn’t matter.

Next I match the file size or <DIR> with

// Group 2 - Matches the file size or <DIR>
(<DIR>|\d+)

Catching the result in a group.

The last part matches directory names or file names

// Group 3 - Matches the dir/file name
(.+)

Now that we captured all groups we can parse the values:

DateTime.Parse(g[1].Value); // be careful with current culture
                            // a different culture may not work

To check if the captured entry is a file or not you can just check if it is <DIR> or a number.

IsFile = g[2].Value != "<DIR>"; // it is a file if it is not <DIR>

And the name is just what is left

Name = g[3].Value; // returns a string

Then you can use the groups to build the object, an example:

public class Files
{
    public DateTime ModifiedTime { get; set; }
    public bool IsFile { get; set; }
    public string Name { get; set; }

    public Files(GroupCollection g)
    {
        ModifiedTime = DateTime.Parse(g[1].Value);
        IsFile = g[2].Value != "<DIR>";
        Name = g[3].Value;
    }
}

static void Main(string[] args)
{
    var p = @"(\d{2}-\d{2}-\d{2} \d{2}:\d{2}(?:PM|AM)) (<DIR>|\d+) (.+)";
    var regex = new Regex(p, RegexOptions.IgnoreCase);

    var m1 = regex.Match("02-17-11 01:39PM <DIR> dec");
    var m2 = regex.Match("05-10-11 07:09PM 87588 output.xlsx");

    // DateTime: 02-17-11 01:39PM
    // IsFile  : false
    // Name    : dec
    var file1 = new Files(m1.Groups);

    // DateTime: 05-10-11 07:09PM
    // IsFile  : true
    // Name    : output.xlsx
    var file2 = new Files(m2.Groups);
}

Further reading

• Regex class
• Regex groups

---

String manipulation method

Another way to achieve this is to split the string which can be much faster:

public class Files
{
    public DateTime ModifiedTime { get; set; }
    public bool IsFile { get; set; }
    public string Name { get; set; }

    public Files(string line)
    {
        // Gets the date part and parse to DateTime
        ModifiedTime = DateTime.Parse(line.Substring(0, 16));

        // Gets the file information part and split
        // in two parts
        var fileBlock = line.Substring(17).Split(new char[] { ' ' }, 2);

        // first part tells if it is a file
        IsFile = fileBlock[0] != "<DIR>";

        // second part tells the name
        Name = fileBlock[1];
    }
}

static void Main(string[] args)
{
    // DateTime: 02-17-11 01:39PM
    // IsFile  : false
    // Name    : dec
    var file3 = new Files("02-17-11 01:39PM <DIR> dec");

    // DateTime: 05-10-11 07:09PM
    // IsFile  : true
    // Name    : out put.xlsx
    var file4 = new Files("05-10-11 07:09PM 87588 out put.xlsx");
}

Further reading

• String split
• String.Split Method (Char[], Int32)