Php search string (with wildcards)

Question

Is there a way to put a wildcard in a string? The reason why I am asking is because currently I have a function to search for a substring between two substrings (i.e grab th

Answer 1

I agree that regex are much more flexible than wildcards, but sometimes all you want is a simple way to define patterns. For people looking for a portable solution (not *NIX only) here is my implementation of the function:

function wild_compare($wild, $string) {
    $wild_i = 0;
    $string_i = 0;

    $wild_len = strlen($wild);
    $string_len = strlen($string);

    while ($string_i < $string_len && $wild[$wild_i] != '*') {
        if (($wild[$wild_i] != $string[$string_i]) && ($wild[$wild_i] != '?')) {
            return 0;
        }
        $wild_i++;
        $string_i++;
    }

    $mp = 0;
    $cp = 0;

    while ($string_i < $string_len) {
        if ($wild[$wild_i] == '*') {
            if (++$wild_i == $wild_len) {
                return 1;
            }
            $mp = $wild_i;
            $cp = $string_i + 1;
        }
        else
        if (($wild[$wild_i] == $string[$string_i]) || ($wild[$wild_i] == '?')) {
            $wild_i++;
            $string_i++;
        }
        else {
            $wild_i = $mp;
            $string_i = $cp++;
        }
    }

    while ($wild[$wild_i] == '*') {
        $wild_i++;
    }

    return $wild_i == $wild_len ? 1 : 0;
}

Naturally the PHP implementation is slower than fnmatch(), but it would work on any platform.

It can be used like this:

if (wild_compare('regex are * useful', 'regex are always useful') == 1) {
    echo "I'm glad we agree on this";
}

Answer 2

If you insist to use wildcard (and yes, PREG is much better) you can use function fnmatch which works only on *NIX.

Cheers

Answer 3

Use a regex.

$string = "My dog has fleas";
if (preg_match("/\S+ (\S+) has fleas/", $string, $matches))
  echo ($matches[1]);
else
  echo ("Not found");

\S means any non-space character, + means one or more of the previous thing, so \S+ means match one or more non-space characters. (…) means capture the content of the submatch and put into the $matches array.

Answer 4

wildcard pattern could be converted to regex pattern like this

function wildcard_match($pattern, $subject) {
  $pattern = strtr($pattern, array(
    '*' => '.*?', // 0 or more (lazy) - asterisk (*)
    '?' => '.', // 1 character - question mark (?)
  ));
  return preg_match("/$pattern/", $subject);
}

if string contents special characters, e.g. \.+*?^$|{}/'#, they should be \-escaped

don't tested:

function wildcard_match($pattern, $subject) {
  // quotemeta function has most similar behavior,
  // it escapes \.+*?^$[](), but doesn't escape |{}/'#
  // we don't include * and ?
  $special_chars = "\.+^$[]()|{}/'#";
  $special_chars = str_split($special_chars);
  $escape = array();
  foreach ($special_chars as $char) $escape[$char] = "\\$char";
  $pattern = strtr($pattern, $escape);
  $pattern = strtr($pattern, array(
    '*' => '.*?', // 0 or more (lazy) - asterisk (*)
    '?' => '.', // 1 character - question mark (?)
  ));
  return preg_match("/$pattern/", $subject);
}

Answer 5

This is one of the few cases where regular expressions are actually helpful. :)

if (preg_match('/my (\w+) has/', $str, $matches)) {
    echo $matches[1];
}

See the documentation for preg_match.