CODEWITHSUNDEEP
javascriptphpregex
CodeRonin
CodeRonin

Reputation: 2109

Regular expression for a name that can contain not more than one space character

I'm struggling to find a regular expression that matches a name that can contain a space in it. So far this is what I've tried:

^(?![\s]+$)(?![\s]{2,})[a-zA-Z\s]{2,25}$

Unfortunately I'm not so good on regex. The name can contain only letters and optionally a space character, and if a space is present there must be no more than one space character in the word. The whole name length (counting also the space) must be between 2 and 25 characters long. Here some examples of names that have to match:

Here some examples of names that have not to match the regular expression:

The last requirement is that I have to use this regular expression both in javascript and php.

Thanks in advance!

Upvotes: 0

Views: 1526

Answers (2)

Cary Swoveland
Cary Swoveland

Reputation: 110685

You could match the string with the following regular expression.

^(?!.* .* )[a-zA-Z ]{2,25}$

Demo

The elements of the expression are as follows.

^                # match beginning of string
(?!.* .* )       # negative lookahead asserts the string does not
                 # contain two (or more) spaces
[a-zA-Z ]{2,25}  # match between 2 and 25 letters and spaces
$                # match end of string

Upvotes: 3

The fourth bird
The fourth bird

Reputation: 163362

The pattern ^(?![\s]+$)(?![\s]{2,})[a-zA-Z\s]{2,25}$ that you tried matches:

  • Assert that the string does not consist of 1 or more whitespace chars ^(?![\s]+$)
  • Asserts not 2 or more whitespace chars at the beginning (?![\s]{2,})
  • Match 2-25 chars being either a-zA-Z or a whitespace char [a-zA-Z\s]{2,25}$

There is no restriction to match a single space in the whole string

Note that \s could also match a newline or a tab.

What you could do is assert 2-25 characters in the string.

Then match 1+ chars a-zA-Z and optionally match a single space and 1+ chars a-zA-Z

^(?=.{2,25}$)[a-zA-Z]+(?: [a-zA-Z]+)?$

The pattern matches:

  • ^ Start of string
  • (?=.{2,25}$) Positive lookahead, assert 2-25 chars in the string
  • [a-zA-Z]+ Match 1+ chars A-Za-z
  • (?: [a-zA-Z]+)? Optionally match and again 1+ chars from the character class
  • $ End of string

See a regex demo.

Upvotes: 2

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