PHP/String/preg replace

$0 is set to the whole match, then $1, $2

   <source lang="html4strict">

<?

   $match = "/the (car|cat) sat on the (drive|mat)/";
   $input = "the cat sat on the mat";
   print preg_replace($match, "Matched $0, $1, and $2\n", $input);

?>

 </source>
   
  

Converting Line Breaks

   <source lang="html4strict">

<?php function line_break_set($subject, $type) {

   switch ($type) {
       case "mac":
           $ending = "\r";
           break;
       case "pc":
           $ending = "\r\n";
           break;
       default:
           $ending = "\n";
   }
   return preg_replace("/\r\n|\n\r|\n|\r/", $ending, $subject);

} $str = "Multiple\rtypes of\n\rline breaks\r\nhave been placed within this string\n\nSee?"; $mac = line_break_set($str, "mac"); $unix = line_break_set($str, "unix"); $pc = line_break_set($str, "pc");

echo "

mac = ", addcslashes($mac, "\n\r"), "\npc = ",
    addcslashes($pc, "\n\r"), "\nunix = ",
    addcslashes($unix, "\n\r"), "

";

?>

 </source>
   
  

e modifier treats the replacement string in preg_replace() as if it were PHP.

   <source lang="html4strict">

<? function convDate( $month, $day, $year ) {

 $year = ($year < 70 )?$year+2000:$year;
 $time = ( mktime( 0,0,0,$month,$day,$year) );
 return date("l d F Y", $time);

} $dates = "3/18/03
\n7/22/04"; $dates = preg_replace( "/([0-9]+)\/([0-9]+)\/([0-9]+)/e","convDate($1,$2,$3)", $dates); print $dates; ?>

 </source>
   
  

Entity encoding matched text

   <source lang="html4strict">

<?php $html = "The <b> tag makes text bold: <b>bold</b>"; print preg_replace("@(.*?)@e","html_entity_decode("$1")", $html); ?>

 </source>
   
  

Escape a > character in HTML

   <source lang="html4strict">

<?php

$html = "

replace > and >> and >>>

";

 print "Original text was: "" . $html . ""\n";
 $html = strrev( $html );
 $newhtml = preg_replace( "/>(?![^><]+?\/?<)/", ";tl&", $html );
 $newhtml = strrev( $newhtml );
 print "<b>New text is: "" . $newhtml . ""\n";

?>

 </source>
   
  

Escaping Special Characters

   <source lang="html4strict">

<?php

$html = "

replace > and >> and >>>

";

   print "<b>Original text was: "" . $html . ""\n";
   $html = strrev( $html );
   $newhtml = preg_replace( "/>(?![^><]+?\/?<)/", ";tl&", $html );
   $newhtml = strrev( $newhtml );
   print "<b>New text is: "" . $newhtml . ""\n";

?>

 </source>
   
  

Formatting a Phone Number

   <source lang="html4strict">

<?php $regex = "/^(\(?\d{3}\)?)?[- .]?(\d{3})[- .]?(\d{4})$/";

$values = array("1235551234","800.555.1234", "123-555-1234" ); foreach ($values as $value) {

   $formattedValue = preg_replace($regex, "(\\1) \\2-\\3", $value); 
   echo $formattedValue . "\n"; 

} ?>

 </source>
   
  

Pass a fourth parameter to preg_replace( ) to specify the maximum number of replacements you want to make.

   <source lang="html4strict">

<?

   $a = "Foo moo boo tool foo";
   $b = preg_replace("/[A-Za-z]oo\b/e", "strtoupper("$0")", $a, 2);
   print $b;

?>

 </source>
   
  

pass arrays as parameter one and parameter two, and preg_replace() performs multiple replaces

   <source lang="html4strict">

<?

   $a = "Foo moo boo tool foo";
   $b = preg_replace("/[A-Za-z]oo\b/e", "strtoupper("$0")", $a);
   print $b;

?>

 </source>
   
  

Pass arrays of regular expressions and replacement strings to preg_replace().

   <source lang="html4strict">

<? $text = "25/12/2009, 14/5/0210. Copyright 2003"; $regs = array( "|\b(\d+)/(\d+)/(\d+)\b|", "/([Cc]opyright) 2003/" ); $reps = array( "$2/$1/$3", "$1 2004" ); $text = preg_replace( $regs, $reps, $text ); print "$text
"; ?>

 </source>
   
  

preg_replace

   <source lang="html4strict">

<?php

  $text = "This is a link to http://www.wbex.ru/.";
  echo preg_replace("/http:\/\/(.*)\//", "<a href=\"\${0}\">\${0}</a>", $text);

?>

 </source>
   
  

preg_replace with index

   <source lang="html4strict">

<?php

   $s = "m@t.ca";
   echo preg_replace ("/^(\w+)@(\w+)\.(\w{2,4})/", "\1 at \2 dot \3", $s);

?>

 </source>
   
  

Quote escaping in backreference replacements

   <source lang="html4strict">

<?php $html = "<b> It"s bold </b>"; print preg_replace("@(.*?)@e","html_entity_decode("$1")", $html); print "\n"; $html = "<i> "This" is italic. </i>"; print preg_replace("@(.*?)@e","html_entity_decode("$1")", $html); print "\n"; ?>

 </source>
   
  

Regular Expression Replacements

   <source lang="html4strict">

<?

   $a = "Foo moo boo tool foo";
   $b = preg_replace("/[A-Za-z]oo\b/", "Got word: $0\n", $a);
   print $b;

?>

 </source>
   
  

Remove any doubled-up whitespace

   <source lang="html4strict">

<?php $str = " This line contains\tliberal \r\n use of whitespace.\n\n"; $str = preg_replace("/\s(?=\s)/", "", $str); // Echo out: "This line contains liberal use of whitespace."

echo "

{$str}

";

?>

 </source>
   
  

Replace any non-space whitespace, with a space

   <source lang="html4strict">

<?php $str = " This line contains\tliberal \r\n use of whitespace.\n\n";

$str = preg_replace("/[\n\r\t]/", " ", $str);

// Echo out: "This line contains liberal use of whitespace."

echo "

{$str}

";

?>

 </source>
   
  

Replace with regular expression

   <source lang="html4strict">

<?php

 $teststring = ""Hello" and "Goodbye."";
 $greedyresult = preg_replace("/".*"/", ""***"", $teststring);
 $nongreedyresult = preg_replace("/".*?"/", ""***"", $teststring);
 echo "Original: $teststring\n";
 echo "Greedy Replace: $greedyresult\n";
 echo "Non-Greedy Replace: $nongreedyresult\n";

?>

 </source>
   
  

Replacing URLs with Links

   <source lang="html4strict">

<?php

   $hostRegex = "([a-z\d][-a-z\d]*[a-z\d]\.)*[a-z][-a-z\d]*[a-z]";
   $portRegex = "(:\d{1,})?";
   $pathRegex = "(\/[^?<>#\"\s]+)?";
   $queryRegex = "(\?[^<>#\"\s]+)?";
   $urlRegex = "/(?:(?<=^)|(?<=\s))((ht|f)tps?:\/\/" . $hostRegex . $portRegex . $pathRegex . $queryRegex . ")/";
   $str = "http://home.example.ru.";
   $str2 = "http://home.example.ru:8181/index.php";
   echo $urlRegex . "\n";
   $sample1 = preg_replace($urlRegex, "<a href=\"\\1\">\\1</a>", $str);
   $sample2 = preg_replace($urlRegex, "<a href=\"\\1\">\\1</a>", $str2);
   echo $sample1 . "\n";
   echo $sample2 . "\n";

?

 </source>
   
  

Replacing using backreferences

   <source lang="html4strict">

$members=<<<TEXT Name E-Mail Address

---

A i@example.ru D k@example.ru M m@example.org B b@example.net TEXT; print preg_replace("/([^@\s]+)@(([-a-z0-9]+\.)+[a-z]{2,})/",

                  "\\1 at \\2", $members);
 
 </source>
   
  

Replacing with preg_replace()

   <source lang="html4strict">

$members=<<<TEXT Name E-Mail Address

---

A i@example.ru D k@example.ru M m@example.org B b@example.net TEXT; print preg_replace("/[^@\s]+@([-a-z0-9]+\.)+[a-z]{2,}/",

                  "[ address removed ]", $members);
 
 </source>
   
  

Using Back References with preg_replace()

   <source lang="html4strict">

//converts dates in dd/mm/yy format to mm/dd/yy format:

<? $test = "25/12/2000"; print preg_replace("|(\d+)/(\d+)/(\d+)|", "$2/$1/$3", $test); ?>

 </source>
   
  

Using preg_replace() to Replace Patterns

   <source lang="html4strict">

<? $test = "this is a test."; print preg_replace("/a test/", "another test", $test); ?>

 </source>