regex for phrase like'word-word-word'

Zero4 · 06-30-2019, 10:13 PM

Hi
I am trying to create a regex for a phrase like this

Code:

Silver-Surfer-Marvel.jpg

I need the regex to allow it, if there are 2 '-' in the pharse.

syg00 · 06-30-2019, 10:20 PM

You know what you want, so what have you tried ?.

Zero4 · 07-01-2019, 09:41 PM

Well I have tred all sorts of things, All of them on regexr.com. It is easy to match 1 "-"
But matching 2 a little harder. This is the closest I have come so far

/-\w{2}\

Others
/[A-Za-z]-[A-Za-z]-[A-Za-z]\
/\w-\w-\w*\

Turbocapitalist · 07-01-2019, 10:14 PM

Which tool are you using to apply the expression? Perl or sed or something else? In other words, which type of regular expression do you wish to use?

The methods of writing character classes will vary. In perl and perl-compatible regular expressions an alphanumeric character can be written as \w or [[:alpha:]]. In POSIX, it is written as [[:alpha:]] Then there is also Extended POSIX.

In each style there are modifiers to match sequences. {1,} + * and so on. But not the same in all styles.

syg00 · 07-01-2019, 10:49 PM

As mentioned, \w is for a single character - to match a word, you need the "+" modifier which says "one or more". So your last attempt above is very close.
Note that \w is not strictly the same as [[:alpha:]] - if you use underscores for example. I do regularly in filenames in lieu of spaces.

ehartman · 07-02-2019, 04:51 AM

Quote:

Originally Posted by syg00

Note that \w is not strictly the same as [[:alpha:]] - if you use underscores for example. I do regularly in filenames in lieu of spaces.

And filenames quite often do have digits (0-9) too and/or other special characters, like i.e. single quotes. For example this Norah Jones song:

Quote:

Don't_Know_Why_(Live_In_NYC).mp3

which contains underscores, a singe quote and a pair of parentheses.

ehartman · 07-02-2019, 04:56 AM

Quote:

Originally Posted by Turbocapitalist

an alphanumeric character can be written as \w or [[:alpha:]]. In POSIX, it is written as [[:alpha:]]

To be strict [[:alpha:]] is a LETTER (alphabetic character in the current locale), an alphanumeric one is [[:alnum:]]
\w is a synonym for [_[:alnum:]], so the class alnum extended with an underscore.

Zero4 · 07-06-2019, 01:04 AM

Thank you all
I want this to work in php: preg_match()

On reflection, I did not explain it very well

SO the expression "Silver-Surfer-Marvel.jpg"

If this is writen like this,
Surfer-Marvel.jpg
Silver-SurferMarvel.jpg

I want them to fail. It must have both "-"

I hope that help

syg00 · 07-06-2019, 01:33 AM

Given all the help above, you answer is .... ?

MadeInGermany · 07-06-2019, 06:36 AM

word-word-word is \w+-\w+-\w+
(The \w stems from the perl RE and is in a recent glibc)