Question

I’m looking for a PHP PCRE regex to match uri’s that are rewritted with Apache‘s mod_rewrite module. The uri’s are as follow :

/param1/param2/param3/param4

The rules for the uri

• must contain at least one /;
• the params must only allow letters, numbers, - and _;
• there must be zero or more instances of the first two rules;

Answer 1

How about:

if (preg_match("~^(?:/[\w-]+)+/?$~", $string)) {
    # do stuff
}

Explanation:

The regular expression:

(?-imsx:^(?:/[\w-]+)+/?$)

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  ^                        the beginning of the string
----------------------------------------------------------------------
  (?:                      group, but do not capture (1 or more times
                           (matching the most amount possible)):
----------------------------------------------------------------------
    /                        '/'
----------------------------------------------------------------------
    [\w-]+                   any character of: word characters (a-z,
                             A-Z, 0-9, _), '-' (1 or more times
                             (matching the most amount possible))
----------------------------------------------------------------------
  )+                       end of grouping
----------------------------------------------------------------------
  /?                       '/' (optional (matching the most amount
                           possible))
----------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------