CODEWITHSUNDEEP
phpregex
user2686562
user2686562

Reputation: 3

PHP regex to include double backslashes in brackets

So I am trying to do a relatively simple php regex to check wether a string contains one of these characters: .,%$@/0123456789 but I also want to check wether it contains a double backslash (I don't want it to evaluate to true if it only contains one backslash) and I can't figure out how to do it. Any help would be appreciated :)

Here is what I was using so far:

preg_match('/[.,%$@\/0-9]/',$string)

I am not sur how to include the '\\\\' for the double backslash.

Thanks in advance!

Upvotes: 0

Views: 247

Answers (2)

Sammitch
Sammitch

Reputation: 32242

If the string must be made up of the characters you've given, but also must contain a double backslash, but not a single backslash, then as far as I can see you're going to need 3 regular expressions.

if (
  (!preg_match('/[^.,%$@\/\\0-9]/', $string)) // fails if the string contains a character that is not allowed
  &&
  ! (
    preg_match('/\\/', $string) // contains at least one backslash
    &&
    !preg_match('/\\{2}/') // succeeds if the string contains a double-backslash
  )
) { /* code */ }

If you try to combine all your rules into a single regex, you're gonna have a bad time.

There is also the drawback that once the string contains a double-backslash it can then have extra backslashes anywhere, ie '12\3456\78\90' is valid. If this is possible, but not permissible in the input then you might want to consider a regex that strictly checks the format rather than just testing for valid characters.

Upvotes: 0

Michelle
Michelle

Reputation: 2900

You're just looking for your character set or a double backslash, right? So:

preg_match('/[.,%$@\/0-9]|\\\\/',$string)

Where | means "or".

Upvotes: 1

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