nonword metacharacter - \w - Regex - Regular Expression Tutorial

Tutorials

Regular-expression

Topic

How is nonword metacharacter "\w" used in regex?

Explanation

The "\W" metacharacter is used to match any nonword character, and it is equivalent to the pattern [^A-Za-z0-9] in regular expression.

PHP Example:

    <?php
    $str = "ABCDabcd_1239*";
    if (preg_match("/\W/", $str, $matches))
     {echo "Pattern matches!";
      print "<br>";
      echo $matches[0];}
    else 
      {echo "Pattern not matched!";}
    ?>

Result:

    Pattern matches!
    *

In the above example for regex the string "$str" has all word characters that are "[a-z][A-Z][0-9]_" and the only nonword character is "*" which is matched.

Perl Example:

    #! C:\programfiles\perl\bin\perl
    print "content-type: text/html\n\n";
    $str = "ABCDabcd_1239";
    if ($str =~ m/W/)
      {print "It's matched!";} 
    else 
      {print "It's not matched!";}

Result:

    It's not matched!

In the above example for regex the pattern "/\W/" is unmatched, as the string does not have any nonword metacharacter that is "[a-z][A-Z][0-9]_ ".

nonword metacharacter "\w" in Regular Expression