Extract Date from file name using Regex

Question

I have the following structure for names:

GuidAsString/yyyy/MM/dd.zip

An example:

e1e2e854-e1cd-4980-83bb-2a0273f904aa/2018/11/18.zip

I would like to extract the date using regex. Regex is just not my thing.

Update: I am trying to do something like:

DateTime dateTime = DateTime.ParseExact(name, format, formatprovider)

and I am looking for the format. If you have a more elegant way that would be even better.

I would appreciate your help.

@KlausGütter it appears to me the file name is 18.zip, and /2018/ + /11/ are simply subfolders — K.Dᴀᴠɪs
– K.Dᴀᴠɪs, Commented Nov 18, 2018 at 11:10
I am sorry I was not accurate. Please ignore that I wrote file name and consider it a string that I need to extract the date from. Thanx — Akram Shahda
– Akram Shahda, Commented Nov 18, 2018 at 11:12

JohnyL · Accepted Answer · 2018-11-18 11:24:08Z

2

string input = @"e1e2e854-e1cd-4980-83bb-2a0273f904aa/2018/11/18.zip";
string pattern = @"/(\d+/\d+/\d+)";
var match = Regex.Match(input, pattern);
var date = DateTime.Parse(match.Groups[1].Value);
WriteLine(date.ToShortDateString());
// Prints: 18.11.2018

One-liner:

var date = DateTime.Parse(Regex.Match(@"e1e2e854-e1cd-4980-83bb-2a0273f904aa/2018/11/18.zip", @"/(\d+/\d+/\d+)").Groups[1].Value);

edited Nov 18, 2018 at 11:24

answered Nov 18, 2018 at 11:06

JohnyL

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12 Comments

Akram Shahda Over a year ago

I am trying to do something like: DateTime dateTime = DateTime.ParseExact(name, format, formatprovider). I would appreciate if you could provide me with the format here :)

JohnyL Over a year ago

@AkramShahda Well, my first code (see in edited) extracts year, month and time separately. You can do with them whatever you want. :)

Akram Shahda Over a year ago

Thank you but what I really need is a one liner code to get there.

JohnyL Over a year ago

@AkramShahda Added one-liner 😉

Luis Colorado Over a year ago

As the filename format is fixed, using three capture groups wouldn't be better than capture all in one and then having to parse the date again?

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Soner Gönül · Accepted Answer · 2018-11-18 11:30:04Z

2

you could use to extract the date in string format with regex:

var st = "e1e2e854-e1cd-4980-83bb-2a0273f904aa/2018/11/18.zip";
var st1 = Regex.Match(st,@"\d{4}/\d{2}/\d{2}").Value;

st1 = "2018/11/18" if you want to convert in date format use:

var date = DateTime.Parse(st1);

edited Nov 18, 2018 at 11:30

Soner Gönül

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answered Nov 18, 2018 at 11:13

Frenchy

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2 Comments

Akram Shahda Over a year ago

I am trying to do something like: DateTime dateTime = DateTime.ParseExact(name, format, formatprovider). I would appreciate if you could provide me with the format here :)

Luis Colorado Over a year ago

Why not using "/(\\d+)/(\\d+)/(\\d+)" and then use the three captured groups separately to build a date with the native con. Why to parse the date again to separate the three fields?

Soner Gönül · Accepted Answer · 2018-11-18 11:29:24Z

0

You easily find the solution with some string manipulation. You can use String.Split method like;

var str = "e1e2e854-e1cd-4980-83bb-2a0273f904aa/2018/11/18.zip";
var year = str.Split('/')[1];
var month = str.Split('/')[2];
var day = str.Split('/')[3].Split('.')[0];

and you can parse your parts like;

var myDate = DateTime.ParseExact($"{year}{day}{month}",
                                  "yyyyddMM",
                                  CultureInfo.InvariantCulture);

edited Nov 18, 2018 at 11:29

answered Nov 18, 2018 at 11:26

Soner Gönül

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3 Comments

Akram Shahda Over a year ago

Thank you but don't you think it is too much code for one simple purpose?

Soner Gönül Over a year ago

@AkramShahda You don't need regex for that. Use just simple string manipulations. It is not an expensive operation after all. This is just 5 lines of code. Is it really too much? Don't you think it is more readable than regex one? Your choice..

Luis Colorado Over a year ago

@SonerGönül, why don't use regex for that? Do you think that using simple string manipulations (each requiring one pass through the data, at least) will be better than doing all in just one pass? Do you actually think that using .split() three times on the same String will be more efficient than getting the three fields in one shot? Do you know that there are more things than using .split() ???

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