Check for multiple and combination patterns with PHP preg_match

Question

I don't want to allow a multiple patterns in a string, such as,

$string = "php in  stackoverflow"; // multiple spaces not allowed
$string = "php in--stackoverflow"; // multiple hyphens not allowed
$string = "php in__stackoverflow"; // multiple underscores not allowed
etc

So, it works with these lines,

if(preg_match('/\s\s+/', $string)) echo "only a single spaces are allowed";
if(preg_match('/\-\-+/', $string)) echo "only a single hyphens are allowed";
if(preg_match('/\_\_+/', $string)) echo "only a single underscores are allowed";

I also don't want to allow the combination patterns below and the lines above don't work,

$string = "php in -stackoverflow"; // a space with a hyphen not allowed
$string = "php in-_stackoverflow"; // a hyphens with a underscore not allowed
$string = "php in_ stackoverflow"; // a underscore with a space not allowed
etc

Any idea I can achieve this with a simple script?

Do you want to check for two of any of these characters in a row? — dpk2442
– dpk2442, Commented Nov 1, 2012 at 17:48

Jonathan Kuhn · Accepted Answer · 2012-11-01 17:48:31Z

2

This is what character classes are for, matching multiple characters.

if(preg_match('/[\s-_][\s-_]+/', $string)) echo "only a single space, hyphen or underscore is allowed";

answered Nov 1, 2012 at 17:48

Jonathan Kuhn

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