I need to accept the following:

• x{1}.xxxxx{1,40}
• x{1}.xxxxx{1,40}-xxxxx{1,40}
• xxxxx{1,40}
• xxxxx{1,40}-xxxxx{1,40}
• xxxx xxxxx xxxxx{words with space between}

My regex is not working...

/^([a-z]{1}\.[a-z]{1,40}|[a-z]{1}\.[a-z]{1,40}\-[a-z]{1,40}|[a-z\s]{1,})$/i

While

/^([a-z]{1}\.[a-z]{1,40}|[a-z]{1}\.[a-z]{1,40}\-[a-z]{1,40})$/i

alone is working OK and

/^([a-z\s]{1,})$/i

is working OK as well...

What am I doing wrong? Thank you in advance...

CodePudding user response：

You can try with the following regex:

^(([a-z]\.)?[a-z]{1,40}(-[a-z]{1,40})?|[a-z] ( [a-z] ) )$

This solution uses two patterns:

• the first one matches your first four samples:
  • optional first group: [a-z]{1}\.
  • mandatory second group: [a-z]{1,40}
  • optional third group: -[a-z]{1,40}
• the second one matches your last sample:
  • words separated by characters: [a-z] ( [a-z] ) )

These groups will be highlighted separately.

Explanation in detail:

• ^: start of string
• ([a-z]\.)?: one alphabetical character dot (optional group)
• [a-z]{1,40}: from 1 to 40 alphabetical characters
• (-[a-z]{1,40})?: dash 1 to 40 alphabetical characters (optional group)
• [a-z] : combination of alphabetical characters
• ( [a-z] ) : combination of multiple <space combination of characters>
• $: end of string

Try it here.

CodePudding user response：

You might write the pattern as:

^(?:(?:[a-z]\.)?[a-z]{1,40}(?:-[a-z]{1,40})?|[a-z] (?:\s [a-z] ) )$

• ^ Start of string
• (?: Non capture group
  • (?:[a-z]\.)? Match an optional char a-z and a dot
  • [a-z]{1,40} Match 1-40 chars
  • (?:-[a-z]{1,40})? An optional part matching a hyphen and 1-40 chars
  • | Or
  • [a-z] (?:\s [a-z] ) Match 2 or more words with spaces between them
• ) Close the non capture group
• $ End of string

See a regex101 demo.