PHP allow letters and minus but not repeating minus

Question

I would like to allow in any charsets (latin, hebrew, cyrillic but not unicode emojis) all letter and minus (-), but it should not allow to use the minus more then once per time and not on start and end:

YaMo -> OK
Ya-Mo -> OK
Ya-Mo-Ga -> OK
Ya--Mo -> FALSE
Ya---Mo -> FALSE
-Ya -> FALSE
-Ya-Mo- -> FALSE
Ya- -> FALSE
Yo-Mo- Mo -> FALSE
Yo-Mo -Go -> FALSE

So far I have:

preg_match('/^[\p{L} -]+$/', $post['firstname'])

It don't take care about multiple occurence and if is on start or end. Exist there any regex approach to do it?

As workaround I now check with substr first and last letter != '-' and check with strpos for '--'.

the proposed similiar duplicate is wrong, as it not work as it should, it allow: Yo-Mo- Mo

Use `'/^\p{L}+(?:[ -]\p{L}+)*$/u'` - https://regex101.com/r/Uv7NUb/1. I think the hyphen rule also pertains to the space, right? — Wiktor Stribiżew, May 11 '18 at 09:49
I found the [post](https://stackoverflow.com/a/4897392/3832970) where all you need is to replace `[A-Za-z0-9-]+` with your `[\p{L} -]+`. Also, add `u` to make the regex fully Unicode compatible and make PCRE treat the input text as Unicode chars. — Wiktor Stribiżew, May 11 '18 at 09:55
@WiktorStribiżew the proposed duplicate is wrong I found out it don't work as it should. — nenad007, May 11 '18 at 10:09
**Do you want to allow spaces?** If not, *why is it in your pattern?* You say, `Yo-Mo- Mo` should not be matched, but why? If you do not want spaces, try my first suggestion then, but take out space, `'/^\p{L}+(?:-\p{L}+)*$/u'`. — Wiktor Stribiżew, May 11 '18 at 10:22
@Wiktor Stribiżew space is only allowed between two words. Yo-Mo- Mo -> not allowed but Yo-Mo Mo is allowed, the idea behind is to allow real names only. — nenad007, May 11 '18 at 10:26
So, my top comment regex is working for you, right? Please test. — Wiktor Stribiżew, May 11 '18 at 10:26
@WiktorStribiżew yes the top comment solution works, thank you. I concenctrated on the proposed duplicate solution and missed this. — nenad007, May 11 '18 at 10:30

aelor · Answer 1 · 2018-05-11T09:59:03.180

1

try this:

^\w+(-\w+)*$

\w+ matches any word character (equal to [a-zA-Z0-9_]) one or more times
(-\w+)* makes sure that the word characters along with hiphen appears zero or more times

online demo

edited May 11 '18 at 09:59

answered May 11 '18 at 09:53

aelor

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score 1 · Accepted Answer · answered May 11 '18 at 10:31

The regex you may use is

'/^\p{L}+(?:[ -]\p{L}+)*$/u'

See the regex demo.

Details

^ - start of string
\p{L}+ - 1+ letters
(?:[ -]\p{L}+)* - 0+ repetitions of
- [ -] - a space or -
- \p{L}+ - 1+ letters
$ - end of string (replace with \z to only match the very end of string, and not also before a final LF symbol).

The modifier u is necessary to make it work without issues with Unicode strings.

PHP allow letters and minus but not repeating minus

2 Answers2