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regex – php only allow letters, numbers, spaces and specific symbols using pregmatch

Posted by: admin April 23, 2020 Leave a comment

Questions:

on my php i use preg_match to validate input texts.

if(preg_match('/^[a-zA-Z0-9]+$/', $firstname)) {
}

But this only allows alphanumeric and does not allow spaces. I want to allow spaces, alpha and numeric. and period(.) and dash(-)

Please help me out here? thanks in advance.

How to&Answers:

Use

preg_match('/^[a-z0-9 .\-]+$/i', $firstname)

Answer:

If you not only want to allow ASCII, then use Unicode properties:

preg_match('/^[\p{L}\p{N} .-]+$/', $firstname)

\p{L} is any letter in any language, matches also Chinese, Hebrew, Arabic, … characters.

\p{N} any kind of numeric character (means also e.g. roman numerals)

if you want to limit to digits, then use \p{Nd}

Answer:

The only difficult bit here is the dash.

For spaces and dots, you can simply add them to your character class, like so:

'/^[a-zA-Z0-9 .]+$/'

Easy.

The dash is slightly harder because hyphens have special meaning in a character class like this (as you already know, they’re used for ranges of characters like a-z). In order to specify a hyphen in a character class, it must be the first character in the class (ie it must not be between two characters, otherwise it is treated as a character range marker).

So your expression would be:

'/^[-a-zA-Z0-9 .]+$/'

Hope that helps.