RegEx for matching an alphanumeric pattern with quantifier

Question

I am trying to limit the digits between 4 and 6 in my regex but it is not working

Minimum range works but the max range does not work:

Some Text-1 = validates
Some Text-201901 = validates
Some Text-20190101 = passes the validation where it should fail

Now if I add $ at the end then none of the above work.

Code:

^[A-Z ]{3,}-\d{4,6}

@WiktorStribiżew he mentions that this exact solution doesn't work — Not a real meerkat, May 30 '19 at 22:34
That makes sense only if the regex is used in .NET with multiline flag and line endings are CRLF (and then it is a dupe of another question, `\r?$` should be used). Adding `$` generally fixes it, so it is closed correctly. — Wiktor Stribiżew, May 30 '19 at 22:35
@Faisal where do you use this regex? can you add some code? Preferably a [mcve] — Not a real meerkat, May 30 '19 at 22:35
Hi All: Thank you for all of your suggestions . Finally what worked was @sln solution ^[A-Z ]{3,}-[0-9]{3,6}(?!\d) . What does (?!/d) do? — Faisal Shah, May 31 '19 at 15:42
That means you do not want to match the whole string, but a substring at the beginning of a string that is not followed with a digit (the last 4 to 6 digits cannot be followed with a digit). See [this answer](https://stackoverflow.com/a/56401231/3832970). — Wiktor Stribiżew, May 31 '19 at 20:15

score 1 · Accepted Answer · answered May 31 '19 at 20:14

1

You want to use

^[A-Z ]{3,}-[0-9]{3,6}(?!\d)

Details

^ - start of a string
[A-Z ]{3,} - three or more uppercase letters or spaces
- - a hyphen
[0-9]{3,6} - three to six digits
(?!\d) - a negative lookahead that fails the match if, immediately to the right of the current location, there is a digit.

answered May 31 '19 at 20:14

Wiktor Stribiżew

607,720
39
448
563

1

Ty for the explanation – Faisal Shah Jun 03 '19 at 15:26

score 0 · Answer 2 · answered May 31 '19 at 02:20

I'm not quite sure, what we might wish to pass and fail, however based on your original expression my guess is that this might be what we might want to start with with an i flag:

^[A-Z ]{3,}-\d{1,6}$

or without i flag:

^[A-Za-z ]{3,}-\d{1,6}$

Demo

Test

const regex = /^[A-Z ]{3,}-\d{1,6}$/gmi;
const str = `Some Text-1
Some Text-201901
Some Text-20190101`;
let m;

while ((m = regex.exec(str)) !== null) {
    // This is necessary to avoid infinite loops with zero-width matches
    if (m.index === regex.lastIndex) {
        regex.lastIndex++;
    }
    
    // The result can be accessed through the `m`-variable.
    m.forEach((match, groupIndex) => {
        console.log(`Found match, group ${groupIndex}: ${match}`);
    });
}

RegEx

If this expression wasn't desired, it can be modified/changed in regex101.com.

RegEx Circuit

jex.im visualizes regular expressions:

RegEx for matching an alphanumeric pattern with quantifier

2 Answers2

Demo

Test

RegEx

RegEx Circuit