CODEWITHSUNDEEP
phpregexexpression
Asad Sayed
Asad Sayed

Reputation: 11

Regular Expression RegEx for no special characters and atleast one letter

I am trying to create a regular expression that does not allow any special characters, but also requires at least one letter (alphabet) to pass. The alphabet can be capital or lowercase.

Example required pass and fail cases

I would also like to allow -, and _ characters.

This is what I have created so far: ^(?=.*[A-Z]).{3,25}$

The above RegEx checks to make sure that an alphabet exists within the expression, but I would also like to disallow special characters.

Can someone explain how I can add the extra check within the same regular expression?

Upvotes: 1

Views: 1568

Answers (2)

The fourth bird
The fourth bird

Reputation: 163207

If you dont' want to allow - or spaces at the start or at the end, you could use 2 lookahead assertions, 1 for the number of characters and the other one to assert a char A-Z.

^(?=[^A-Z]*[A-Z])(?=.{3,25}$)\w+(?:[\h-]\w+)*$

Explanation

  • ^ Start of string
  • (?=[^A-Z]*[A-Z]) Assert an uppercase char A-Z
  • (?=.{3,25}$) Assert 3 - 25 chars
  • \w+ Match 1+ word chars
  • (?:[\h-]\w+)* Repeat 0+ times matching either a horizontal whitespace char or -
  • $ End of string

Regex demo

Upvotes: 1

user3783243
user3783243

Reputation: 5224

Change the . to be your allowed character list. Something like:

^(?=.*?[A-Z])[\w\h-]{3,25}$

https://regex101.com/r/j4wuUP/2/

[\w\h-]

(\w) allows for a-zA-Z0-9_, (\h) horizontal whitespace, and -s. The - must be first, last, or escaped; otherwise it will create a range of ascii characters. In non-PCRE flavors escaping is not possible so it must be first or last.

Upvotes: 0

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