Regular expressions to match month and year

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4.50/5 (2 votes)

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I want to validate my string for month and year like "June 2016" can any one help me to solve this.

What I have tried:

if (!$("#txtmonthyear").val().trim().match("^[0-9 ]*[a-zA-Z ]+[a-zA-Z0-9 ]*$")) {
return false;
}

Posted 20-Oct-16 1:39am

jaideepsinh

Updated 21-Oct-16 3:24am

Richard MacCutchan

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Richard MacCutchan 20-Oct-16 7:49am

Look at your source data:
1. Starts with upper case [A-Z] (or maybe only the letters of month names)
2. followed by up to 8 lower case [a-z]
3. followed by space
4. followed by four digits, the first one not being 0

Your sample above does not look like it matches.

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Nathan Minier · Answer 1 · 2016-10-20T02:12:00

I regularly use the Regular Expression Library[^] to help find and validate REGEX.

That said, I think it's a good thing to learn how these things work for yourself. MS has some really good references for using REGEX with C#:
Regular Expression Language - Quick Reference[^]

In your case, you want a month and year. We could use the regex to extract them from a string and use a post-submit validator, but it looks like you want a pre-submit so we'll keep it easy.

C#

"^[a-zA-Z]+\s{1}[0-9]{4}$"

This simple validator will simply evaluate that a word is followed by a space is followed by a 4-digit number. Here's the breakdown:
^ Start evalation at the first character of the string.
[a-zA-Z]+ match alphabetic characters, lower and upper case, one or more times.
\s{1} match whitespace exactly once.
[0-9]{4} match a numeric digit exactly 4 times
$ match the string terminator

You can do a hell of a lot more with REGEX should you so choose. It's a superbly useful tool that gets ignored too often due to the oblique syntax.

Richard MacCutchan · Answer 2 · 2016-10-20T01:58:00

Solution 1

Try this:

[ADFJMNOS][a-z]+ [12][0-9][0-9][0-9]\b

which can no doubt be improved upon.

[edit]
Such as:

[ADFJMNOS][a-z]{2,8}\s[12][0-9]{3}\b

[/edit]

Posted 20-Oct-16 1:58am

Richard MacCutchan

Updated 21-Oct-16 0:23am

v3

Comments

jaideepsinh 20-Oct-16 8:16am

I user like this:
if (!$("#txtmonthyear").val().trim().match("^[ADFJMNOS][a-z]+ [12][0-9][0-9][0-9]*$")) {
return false;
}
but not working

Richard MacCutchan 20-Oct-16 8:22am

I tested the above and it worked for two different dates. You need to check exactly what string you are trying to match against.

jaideepsinh 20-Oct-16 9:19am

it is not check last four character is number or not it is only check last character is number.

Richard MacCutchan 20-Oct-16 9:32am

No it does not, you have added an asterisk after the last [0-9]. And you still have not explained what string you are trying to match against.

jaideepsinh 21-Oct-16 3:39am

i am validate this "Ja 20000" and this both not working in my c# code

Richard MacCutchan 21-Oct-16 6:23am

Try adding \b at the end of the mask, as shown in my updates above.

Patrice T · Answer 3 · 2016-10-20T07:23:00

Not a solution, but tools, I recommend last one to debug a RegEx:

Here is a link to RegEx documentation:
perlre - perldoc.perl.org[^]
Here is links to tools to help build RegEx and debug them:
.NET Regex Tester - Regex Storm[^]
Expresso Regular Expression Tool[^]
This one show you the RegEx as a nice graph which is really helpful to understand what is doing a RegEx:
Debuggex: Online visual regex tester. JavaScript, Python, and PCRE.[^]

Peter Leow · Answer 4 · 2016-10-21T03:24:00

If you insist on regex, than try this:

January|February|June\s\d{4}

You will have to fill in the rest of the month names.
However, it is neither efficient nor fool proof to use regex to validate a date as it has far too many formats.
Instead, try DateTime.TryParseExact Method (System)[^]. See example below:

C#

using System;
using System.Globalization;
					
public class Program
{
	public static void Main()
	{
		string input = "June 2016";
		string format = "MMMM yyyy";
		DateTime dateTime;
		if (DateTime.TryParseExact(input, format, CultureInfo.InvariantCulture, DateTimeStyles.None, out dateTime))
		{
	    	//Console.WriteLine(dateTime);
			Console.Write("valid");
		} else {
			Console.Write("Not Valid");
		}		
	}
}

Regular expressions to match month and year

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