PHP: regular expressions

preg_match

<html><head><title>preg_match example with PHP</title></head>
<body>

<table summary='match results'>

<?php

  function does_match($p, $t) {

    print "<tr><td>$t</td><td>";

    if (preg_match($p, $t)) {
      print "matches";
    }
    else {
      print "doesn't match";
    }

    print "</td><td>$p</td></tr>";

  }

  $pattern  = '/foo/i';
  $with_foo = 'I have a Foo.';
  $no_foo   = 'I do not.';

  does_match($pattern, $with_foo);
  does_match($pattern, $no_foo);

  $pattern = '/\[in\]/';
  $in_1    = 'does [in] match?';
  $in_2    = 'does in match?';

  $pattern = '/[in]/';
  $in_1    = 'abcdefgh jklm opqrs uvwxyz';
  $in_2    = 'abdef ghij lm opq stu wxyz';

  does_match($pattern, $in_1);
  does_match($pattern, $in_2);

  $pattern = '/end$/';
  $dollar_1= 'at the end';
  $dollar_2= 'at the end NOT';

  does_match($pattern, $dollar_1);
  does_match($pattern, $dollar_2);

?>

</table>

  <p>See also <a href='preg_replace.html'>preg_replace.html</a>.

</body><html>

Github repository about-php, path: /preg_match.html

See also this example that demonstrates how preg_match is imported into the SQLite engine so that it is possible to query an SQLite table with regular expressions.

preg_replace

In its most basic form, preg_replace takes the following three parameters: preg_replace($pattern, $replacement, $text).

The two optional parameters are limit and count.

<html><head><title>preg_replace example with PHP</title></head>
<body>

<pre>

<?php

  $pattern = '/foo/i';
  $replace = 'bar';
  $text    = 'one foo and another FOO to be replaced';

  print "pattern: " . $pattern . "<br>";
  print "replace: " . $replace . "<br>";
  print "text:    " . $text    . "<br>";
  print "result:  " . preg_replace($pattern, $replace, $text);

?>

</pre>

<h2>preg_replace with arrays</h2>

<code>
<?php

  $text = 'one foo and another FOO to be replaced';

  print "result: " . preg_replace( 
                           array('/foo/i' ,'/ to be /'),
                           array( 'bar'   , ' were '  ),
                           $text);

  print "<p>";

  $text = 'The word is: strawberry';

  #                        Replace from left to right.
  print "result: " . preg_replace(  
                           array( '/strawberry/', '@lemon@', '!orange!'),
                           array(  'lemon'      ,  'orange',  'pear'   ),
                           $text);

?>
</code>

<p>See also <a href='preg_match.html'>preg_match.html</a> and <a href='str_replace.html'>str_replace.html</a>.

</body><html>

Github repository about-php, path: /preg_replace.html

Removing niqquds

Niqquds can be removed with the following regular expression:

$without_niqqud = preg_replace('/[\x{0591}-\x{05C7}]/u', '', $hebrew_word);

TODO

preg_replace_callback

$pattern = '/foo: (\d+)/';
$result = preg_replace_callback(
            $pattern,
            function($m) use ($g_multiplicator) {
              $res = $m[1] * $g_multiplicator;
              return $res;
            }
            $text
          );

`preg_filter`
`preg_grep`
`preg_last_error_msg`
`preg_last_error`
`preg_match_all`
`preg_match`	Tests if a given text matches a regular expressions (by returning a boolean like value) and fills an optional `matches` parameter.
`preg_quote`
`preg_replace_callback_array`
`preg_replace_callback`
`preg_replace`	Uses a regular expression to replace portions of a text with a given replacement
`preg_split`