RegEx for yyyyMMdd format

Posted on 2010-09-14
Medium Priority
Last Modified: 2013-12-16
I have a csv file that has a date column in the following format yyyyMMdd
eg:- 20011114

i want to parse this date via a RegEx into a format that is acceptable by DateTime class in C#

this is what i have done so far (see code section below)

however i am getting an error "Input string was not in a correct format" when the code enters the following line.

if (!ConvertToDate(int.Parse(m.Groups["year"].Value), int.Parse(m.Groups["month"].Value), int.Parse(m.Groups["day"].Value), out date))

m = Regex.Match(str, @"(?<=^(([2-9]\d{3}|1999)((0[1-9]|1[012])(0[1-9]|1\d|2[0-8])|(0[13456789]|1[012])(29|30)|(0[13578]|1[02])31)|(([2-9]\d)(0[48]|[2468][048]|[13579][26])|(([2468][048]|[3579][26])00))0229)$)", RegexOptions.Compiled | RegexOptions.IgnoreCase);
            if (m.Success)
                DateTime date;
                if ((defaultFormat ^ DateTimeFormat.USA_DATE) == DateTimeFormat.USA_DATE)
                    if (!ConvertToDate(int.Parse(m.Groups["year"].Value), int.Parse(m.Groups["day"].Value), int.Parse(m.Groups["month"].Value), out date))
                        return false;
                    if (!ConvertToDate(int.Parse(m.Groups["year"].Value), int.Parse(m.Groups["month"].Value), int.Parse(m.Groups["day"].Value), out date))
                        return false;
                parsedDate = new ParsedDateTime(m.Index, m.Length, -1, -1, date);
                return true;

Open in new window

Question by:2ooth
LVL 40

Expert Comment

by:Gurvinder Pal Singh
ID: 33670084
Assuming that month and date starts from 0
LVL 40

Assisted Solution

by:Gurvinder Pal Singh
Gurvinder Pal Singh earned 1000 total points
ID: 33670103
or just this
Dim D As Date = Date.ParseExact(X, "yyyyMMdd", Nothing);
from here

LVL 13

Expert Comment

by:Naman Goel
ID: 33670128
You can refer to following link
Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

LVL 10

Accepted Solution

Mathiyazhagan earned 1000 total points
ID: 33670355
I too suggest you to go with DateTime functions as it assures valid date. you can do it with TryParseExact method and  cultureInfo.have attched sample code; hope this helps.
private bool GetValidDate(string str,bool IsUSCulture,out DateTime date)
            System.Globalization.CultureInfo culture = System.Globalization.CultureInfo.InvariantCulture;
            if (IsUSCulture)
                culture = new System.Globalization.CultureInfo("en-US");
            return DateTime.TryParseExact(str, "yyyyMMdd", culture , System.Globalization.DateTimeStyles.None, out date);

//using the above code

 DateTime d;
            if (GetValidDate("20011114", true , out d))
                //work with valid date d

Open in new window

LVL 75

Expert Comment

by:käµfm³d 👽
ID: 33672047
I also agree that you should use the Parse group of methods which are members of the DateTime struct.

Author Closing Comment

ID: 33679998
Thanks Guys!!!

Featured Post

Train for your Pen Testing Engineer Certification

Enroll today in this bundle of courses to gain experience in the logistics of pen testing, Linux fundamentals, vulnerability assessments, detecting live systems, and more! This series, valued at $3,000, is free for Premium members, Team Accounts, and Qualified Experts.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

We are witnesses that everyone is saying that our children shouldn't "play" with a technology because it is dangerous. This article is going to prove that they are wrong.
The PowerShell Core 6.0 of .NET release is just the beginning. The upcoming PowerShell Core 6.1 would have artificial intelligence and internet of things capabilities. So many things to look forward to in the upcoming release.
Learn how to match and substitute tagged data using PHP regular expressions. Demonstrated on Windows 7, but also applies to other operating systems. Demonstrated technique applies to PHP (all versions) and Firefox, but very similar techniques will w…
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…

607 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question