YYYYMMDD Date Format Regular expression for checking date in C # .net

Question

I need to check the date format using a regex in C #.

Here is the format: "YYYYMMDD"

Answer 1

Regular expressions are not suitable for this task. For example, it is difficult to write a regular expression that matches a valid date of "20080229" but not an invalid date of "20100229".

Instead, you should use DateTime.TryParseExactwith a format string "yyyyMMdd". Here is an example:

string s = "20100229";
DateTime result;
if (!DateTime.TryParseExact(
     s,
     "yyyyMMdd",
     CultureInfo.InvariantCulture,
     DateTimeStyles.AssumeUniversal,
     out result))
{
    Console.WriteLine("Invalid date entered.");
};

Answer 2

, , - . 1582 , . . , 1600 - , 1700 , . 1582 9999.

var yyyymmdd = new RegExp("^(?:(?:(?:(?:(?:[13579][26]|[2468][048])00)|(?:[0-9]{2}(?:(?:[13579][26])|(?:[2468][048]|0[48]))))(?:(?:(?:09|04|06|11)(?:0[1-9]|1[0-9]|2[0-9]|30))|(?:(?:01|03|05|07|08|10|12)(?:0[1-9]|1[0-9]|2[0-9]|3[01]))|(?:02(?:0[1-9]|1[0-9]|2[0-9]))))|(?:[0-9]{4}(?:(?:(?:09|04|06|11)(?:0[1-9]|1[0-9]|2[0-9]|30))|(?:(?:01|03|05|07|08|10|12)(?:0[1-9]|1[0-9]|2[0-9]|3[01]))|(?:02(?:[01][0-9]|2[0-8])))))$");

var yyyyDashMmDashDd = new RegExp("^(?:(?:(?:(?:(?:[13579][26]|[2468][048])00)|(?:[0-9]{2}(?:(?:[13579][26])|(?:[2468][048]|0[48]))))-(?:(?:(?:09|04|06|11)-(?:0[1-9]|1[0-9]|2[0-9]|30))|(?:(?:01|03|05|07|08|10|12)-(?:0[1-9]|1[0-9]|2[0-9]|3[01]))|(?:02-(?:0[1-9]|1[0-9]|2[0-9]))))|(?:[0-9]{4}-(?:(?:(?:09|04|06|11)-(?:0[1-9]|1[0-9]|2[0-9]|30))|(?:(?:01|03|05|07|08|10|12)-(?:0[1-9]|1[0-9]|2[0-9]|3[01]))|(?:02-(?:[01][0-9]|2[0-8])))))$");

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Regexper, .

Answer 3

Use DateTime.TryParseExact to check the date. You can use this method to simultaneously check and read the DateTime value.

For instance:

DateTime dateValue;
if (DateTime.TryParseExact(dateString, "yyyyMMdd", CultureInfo.InvariantCulture, DateTimeStyles.None, out dateValue))
{
 //Parsed Successfully   
}