strtr

lichail at sohu dot com (2013-06-22 01:11:38)

<?php
//note this output null
echo strtr('abc', array('' => ''));
?>

vova at 77xy dot net (2013-04-18 08:33:22)

str_tr is 5-10% faster than str_replace

<?php
 
function f1() {
  for($i=0; $i<1000000; ++$i) {
    $new_string = strtr("aboutdealers.com", ".com", "");
  }
}
function f2() {
  for($i=0; $i<1000000; ++$i) {
    $new_string = str_replace("aboutdealers.com", ".com", "");
  }
}
$start = microtime(true);
f1();
$stop = microtime(true);
$time1 = $stop - $start;
 
$start = microtime(true);
f2();
$stop = microtime(true);
$time2 = $stop - $start;
 
echo $time1 . "\t";
echo $time2 . "\n";

Hayley Watson (2013-02-01 02:04:53)

Since strtr (like PHP's other string functions) treats strings as a sequence of bytes, and since UTF-8 and other multibyte encodings use - by definition - more than one byte for at least some characters, the three-string form is likely to have problems. Use the associative array form to specify the mapping.

<?php
// Assuming UTF-8
$str = '?bc ?bc'; // strtr() sees this as nine bytes (including two for each ?)
echo strtr($str, '?', 'a'); // The second argument is equivalent to the string "\xc3\x84" so "\xc3" gets replaced by "a" and the "\x84" is ignored

echo strtr($str, array('?' => 'a')); // Works much better
?>

qeremy [atta] gmail [dotta] com (2013-01-22 19:19:22)

Weird, but strtr corrupting chars, if used like below and if file is encoded in UTF-8;

<?php
$str = '?bc ?bc';
echo strtr($str, '?', 'a');
// output: a?bc a?bc
?>

And a simple solution;

<?php
function strtr_unicode($str, $a = null, $b = null) {
    $translate = $a;
    if (!is_array($a) && !is_array($b)) {
        $a = (array) $a;
        $b = (array) $b;
        $translate = array_combine(
            array_values($a),
            array_values($b)
        );
    }
    // again weird, but accepts an array in this case
    return strtr($str, $translate);
}

$str = '?bc ?bc';
echo strtr($str, '?', 'a') ."\n";
echo strtr_unicode($str, '?', 'a') ."\n";
echo strtr_unicode($str, array('?' => 'a')) ."\n";
// outputs
// a?bc a?bc
// abc abc
// abc abc
?>

Tedy (2012-11-01 20:43:50)

Since strtr() is twice faster than strlwr I decided to write my own lowering function which also handles UTF-8 characters.

<?php

function strlwr($string, $utf = 1)
{
    $latin_letters = array('?' => 'a',
                            '?' => 'a',
                            '?' => 'i',
                            '?' => 's',
                            '?' => 's',
                            '?' => 't',
                            '?' => 't');
                            
    $utf_letters = array('?' => '?',
                        '?' => '?',
                        '?' => '?',
                        '?' => '?',
                        '?' => '?',
                        '?' => '?',
                        '?' => '?');
                      
    $letters = array('A' => 'a',
                    'B' => 'b',
                    'C' => 'c',
                    'D' => 'd',
                    'E' => 'e',
                    'F' => 'f',
                    'G' => 'g',
                    'H' => 'h',
                    'I' => 'i',
                    'J' => 'j',
                    'K' => 'k',
                    'L' => 'l',
                    'M' => 'm',
                    'N' => 'n',
                    'O' => 'o',
                    'P' => 'p',
                    'Q' => 'q',
                    'R' => 'r',
                    'S' => 's',
                    'T' => 't',
                    'U' => 'u',
                    'V' => 'v',
                    'W' => 'w',
                    'X' => 'x',
                    'Y' => 'y',
                    'Z' => 'z');
    
    return ($utf == 1) ? strtr($string, array_merge($utf_letters, $letters)) : strtr($string, array_merge($latin_letters, $letters));
}

?>

This allows you to lower every character (even UTF-8 ones) if you don't set the second parameter, or just lower the UTF-8 ones into their specific latin characters (used when making friendly-urls for example). 

I used romanian characters but, of course, you can add your own local characters. 

Feel free to use/modify this function as you wish. Hope it helps.

patrick dot rauchfuss at gmail dot com (2012-08-24 08:04:07)

Here my solution of an classes recursive caseinsentive strtr..

<?php
class String
{
    public static function stritr(&$string, $from, $to = NULL)
    {
        if(is_string($from))
            $string = preg_replace("'$from'i", $to, $string);

        else if(is_array($from))
        {
            foreach ($from as $key => $val)
                self::stritr($string, $key, $val);
        }
        
        return $string;
    }
}

// example:
$string = "Hello world. This is just a simple test";
print String::stritr($string, 'WorLd', 'foo');

// array example:
print String::stritr($string, array('WorLd' => 'foo', 'TEST' => 'bar'));
?>

antimoz at gmail dot com (2012-02-09 03:08:35)

Here is my array for char normalization:
<?php
        $normalizeChars = array(
            '?'=>'A', '?'=>'A', '?'=>'A', '?'=>'A', '?'=>'A', '?'=>'A', '?'=>'AE', '?'=>'C',
            '?'=>'E', '?'=>'E', '?'=>'E', '?'=>'E', '?'=>'I', '?'=>'I', '?'=>'I', '?'=>'I', '?'=>'Eth',
            '?'=>'N', '?'=>'O', '?'=>'O', '?'=>'O', '?'=>'O', '?'=>'O', '?'=>'O',
            '?'=>'U', '?'=>'U', '?'=>'U', '?'=>'U', '?'=>'Y',
    
            'á'=>'a', 'à'=>'a', '?'=>'a', '?'=>'a', '?'=>'a', '?'=>'a', '?'=>'ae', '?'=>'c',
            'é'=>'e', 'è'=>'e', 'ê'=>'e', '?'=>'e', 'í'=>'i', 'ì'=>'i', '?'=>'i', '?'=>'i', '?'=>'eth',
            '?'=>'n', 'ó'=>'o', 'ò'=>'o', '?'=>'o', '?'=>'o', '?'=>'o', '?'=>'o',
            'ú'=>'u', 'ù'=>'u', '?'=>'u', 'ü'=>'u', '?'=>'y',
            
            '?'=>'sz', '?'=>'thorn', '?'=>'y'
        );
?>

Sam (2012-02-01 22:33:40)

Case Insensitive strtr

<?php
function stritr($string, $one, $two=null) {
    if (is_string($one)) {
        return strtr($string, strtoupper($one) . strtolower($one), "$two$two");
    } else if (is_array($one)) {
        $strReturn = $string
        foreach ($one as $key => $val) {
            $strReturn = preg_replace("'$key'i", $val, $strReturn);
        }
        return $strReturn;
    }
    return $string;
}
?>

Michael Schuijff (2011-10-24 10:02:25)

I found that this approach is often faster than strtr() and won't change the same thing in your string twice (as opposed to str_replace(), which will overwrite things in the order of the array you feed it with):

<?php
function replace ($text, $replace) {
    $keys = array_keys($replace);
    $length = array_combine($keys, array_map('strlen', $keys));
    arsort($length);
    
    $array[] = $text;
    $count = 1;
    reset($length);
    while ($key = key($length)) {
        if (strpos($text, $key) !== false) {
            for ($i = 0; $i < $count; $i += 2) {
                if (($pos = strpos($array[$i], $key)) === false) continue;
                array_splice($array, $i, 1, array(substr($array[$i], 0, $pos), $replace[$key], substr($array[$i], $pos + strlen($key))));
                $count += 2;
            }
        }
        next($length);
    }
    return implode($array);
}
?>

Chris (2011-02-04 12:49:03)

Hope this is useful when you need to see ASCII control characters:
<?php
$xlate = array(chr(0) => '^@/NUL/null', chr(1) => '^A/SOH/start of heading', chr(2) => '^B/STX/start of text', chr(3) => '^C/ETX/end of text', chr(4) => '^D/EOT/end of transmisssion', chr(5) => '^E/ENQ/enquiry', chr(6) => '^F/ACK/acknowledge', chr(7) => '^G/BEL/bell', chr(8) => '^H/BS/backspace', chr(9) => '^I/TAB/horizontal tab', chr(10) => '^J/LF/NL/line feed/new line', chr(11) => '^K/VT/vertical tab', chr(12) => '^L/FF/NP/form feed/new page/', chr(13) => '^M/CR/carrige return', chr(14) => '^N/SO/shift out', chr(15) => '^O/SI/shift in', chr(16) => '^P/DLE/data link escape', chr(17) => '^Q/DC1/device control 1', chr(18) => '^R/DC2/device control 2', chr(19) => '^S/DC3/device control 3', chr(20) => '^T/DC4/device control 4', chr(21) => '^U/NAK/negative acknowledge', chr(22) => '^V/SYN/synchronous idle', chr(23) => '^W/ETB/end of transmission block', chr(24) => '^X/CAN/cancel', chr(25) => '^Y/EM/end of medium', chr(26) => '^Z/SUB/substiute', chr(27) => '^[/ESC/escape', chr(28) => '^\/FS/file separator', chr(29) => '^]/GS/group separator', chr(30) => '^^/RS/record separator', chr(31) => '^_/US/unit separator', chr(32) => 'Space');

$x = 0;
$pad = strlen(strlen($str));
while(isset($str[$x]))
   echo 'character ', str_pad($x+1, $pad), ' = ', strtr($str[$x], $xlate), ' (ascii ', ord($str[$x++]), ')';
?>

elloromtz at gmail dot com (2010-04-19 17:08:56)

If you supply 3 arguments and the 2nd is an array, strtr will search the "A" from "Array" (because you're treating it as a scalar string) and replace it with the 3rd argument:
strtr('Analogy', array('x'=>'y'), '_'); //'_nalogy'
so in reality the above code has the same affect as:
strtr('Analogy', 'A' , '_');

Anonymous (2009-11-25 00:09:40)

Here's a one-liner to strip out non-standard ascii characters, inspired by joeldegan AT yahoo's post below.

<?php
  $new = preg_replace("/[^\x9\xA\xD\x20-\x7F]/", "", $old);
?>

nvyktor (2009-09-09 07:02:58)

Hi all,

as u probably know the is some truoble with the (for example) hungarian special characters. If I used the htmlentities() function, the simple chars had benn converted to the basic format, for example: & aacute;. However this was very simple, some cases it needs more transformation.

As I would like to use the correct caracters even in php, html, js, and more, a wrote this short code to solve this issue:

<?php
function charcode ($text) {
    $text = htmlentities($text); //to convert the simple spec chars
    $search = array("& otilde;","&O tilde;","& ucirc;","&U circ;");
    $replace = array("& #337;","& #336;","& #369;","& #368;");
    $text = str_replace($search, $replace, $text);
    return $text;
}
?>

Now I am able to display any spec chars in any browser with any character encoding set.

Hope U will find this helpful.

Vyktor

allixsenos at gmail dot com (2009-05-16 08:55:08)

fixed "normaliza" functions written below to include Slavic Latin characters... also, it doesn't return lowercase any more (you can easily get that by applying strtolower yourself)...

also, renamed to normalize()

<?php

function normalize ($string) {
    $table = array(
        '?'=>'S', '?'=>'s', '?'=>'Dj', '?'=>'dj', '?'=>'Z', '?'=>'z', '?'=>'C', '?'=>'c', '?'=>'C', '?'=>'c',
        '?'=>'A', '?'=>'A', '?'=>'A', '?'=>'A', '?'=>'A', '?'=>'A', '?'=>'A', '?'=>'C', '?'=>'E', '?'=>'E',
        '?'=>'E', '?'=>'E', '?'=>'I', '?'=>'I', '?'=>'I', '?'=>'I', '?'=>'N', '?'=>'O', '?'=>'O', '?'=>'O',
        '?'=>'O', '?'=>'O', '?'=>'O', '?'=>'U', '?'=>'U', '?'=>'U', '?'=>'U', '?'=>'Y', '?'=>'B', '?'=>'Ss',
        'à'=>'a', 'á'=>'a', '?'=>'a', '?'=>'a', '?'=>'a', '?'=>'a', '?'=>'a', '?'=>'c', 'è'=>'e', 'é'=>'e',
        'ê'=>'e', '?'=>'e', 'ì'=>'i', 'í'=>'i', '?'=>'i', '?'=>'i', '?'=>'o', '?'=>'n', 'ò'=>'o', 'ó'=>'o',
        '?'=>'o', '?'=>'o', '?'=>'o', '?'=>'o', 'ù'=>'u', 'ú'=>'u', '?'=>'u', '?'=>'y', '?'=>'y', '?'=>'b',
        '?'=>'y', '?'=>'R', '?'=>'r',
    );
    
    return strtr($string, $table);
}

?>

Sidney Ricardo (2008-09-05 11:54:36)

This work fine to me:

<?php
function normaliza ($string){
    $a = '??????????????????????????????
?àá??????èéê?ìí????òó????ùú???????';
    $b = 'aaaaaaaceeeeiiiidnoooooouuuuy
bsaaaaaaaceeeeiiiidnoooooouuuyybyRr'; 
    $string = utf8_decode($string);     
    $string = strtr($string, utf8_decode($a), $b);
    $string = strtolower($string);
    return utf8_encode($string);
}
?>

jorge at seisbits dot com (2008-07-11 12:04:12)

If you try to make a strtr of not usual charafters when you are in a utf8 enviroment, you can do that:
function normaliza ($string){
$string = utf8_decode($string);
$string = strtr($string, utf8_decode(" ??????"), "-AEIOU");
$string = strtolower($string);
return $string;
}

dot dot dot dot dot alexander at gmail dot com (2008-03-25 16:09:44)

OK, I debugged the function (had some errors)
Here it is:
if(!function_exists("stritr")){
function stritr($string, $one = NULL, $two = NULL){
/*
stritr - case insensitive version of strtr
Author: Alexander Peev
Posted in PHP.NET
*/
if( is_string( $one ) ){
$two = strval( $two );
$one = substr( $one, 0, min( strlen($one), strlen($two) ) );
$two = substr( $two, 0, min( strlen($one), strlen($two) ) );
$product = strtr( $string, ( strtoupper($one) . strtolower($one) ), ( $two . $two ) );
return $product;
}
else if( is_array( $one ) ){
$pos1 = 0;
$product = $string;
while( count( $one ) > 0 ){
$positions = array();
foreach( $one as $from => $to ){
if( ( $pos2 = stripos( $product, $from, $pos1 ) ) === FALSE ){
unset( $one[ $from ] );
}
else{
$positions[ $from ] = $pos2;
}
}
if( count( $one ) <= 0 )break;
$winner = min( $positions );
$key = array_search( $winner, $positions );
$product = ( substr( $product, 0, $winner ) . $one[$key] . substr( $product, ( $winner + strlen($key) ) ) );
$pos1 = ( $winner + strlen( $one[$key] ) );
}
return $product;
}
else{
return $string;
}
}/* endfunction stritr */
}/* endfunction exists stritr */

dot dot dot dot dot alexander at gmail dot com (2008-03-25 10:44:30)

Here is the stritr I always needed... I wrote it in 15 minutes... But only after the idea struck me. Hope you find it helpful, and enjoy...
<?php
if(!function_exists("stritr")){
    function stritr($string, $one = NULL, $two = NULL){
/*
stritr - case insensitive version of strtr
Author: Alexander Peev
Posted in PHP.NET
*/
        if(  is_string( $one )  ){
            $two = strval( $two );
            $one = substr(  $one, 0, min( strlen($one), strlen($two) )  );
            $two = substr(  $two, 0, min( strlen($one), strlen($two) )  );
            $product = strtr(  $string, ( strtoupper($one) . strtolower($one) ), ( $two . $two )  );
            return $product;
        }
        else if(  is_array( $one )  ){
            $pos1 = 0;
            $product = $string;
            while(  count( $one ) > 0  ){
                $positions = array();
                foreach(  $one as $from => $to  ){
                    if(   (  $pos2 = stripos( $product, $from, $pos1 )  ) === FALSE   ){
                        unset(  $one[ $from ]  );
                    }
                    else{
                        $positions[ $from ] = $pos2;
                    }
                }
                $winner = min( $positions );
                $key = array_search(  $winner, $positions  );
                $product = (   substr(  $product, 0, $winner  ) . $positions[$key] . substr(  $product, ( $winner + strlen($key) )  )   );
                $pos1 = (  $winner + strlen( $positions[$key] )  );
            }
            return $product;
        }
        else{
            return $string;
        }
    }/* endfunction stritr */
}/* endfunction exists stritr */
?>

Jean-Marc Libs (2008-02-26 09:49:07)

A couple of people have suggested examples of use of strstr() in order to do conversions from one charset to the other.
I would like to point out that this is the purpose of iconv().

troelskn at gmail dot com (2008-01-23 15:39:47)

Here's another transcribe function. This one converts cp1252 (aka. Windows-1252) into iso-8859-1 (aka. latin1, the default PHP charset). It only transcribes the few exotic characters, which are unique to cp1252.
function transcribe_cp1252_to_latin1($cp1252) {
return strtr(
$cp1252,
array(
"\x80" => "e", "\x81" => " ", "\x82" => "'", "\x83" => 'f',
"\x84" => '"', "\x85" => "...", "\x86" => "+", "\x87" => "#",
"\x88" => "^", "\x89" => "0/00", "\x8A" => "S", "\x8B" => "<",
"\x8C" => "OE", "\x8D" => " ", "\x8E" => "Z", "\x8F" => " ",
"\x90" => " ", "\x91" => "`", "\x92" => "'", "\x93" => '"',
"\x94" => '"', "\x95" => "*", "\x96" => "-", "\x97" => "--",
"\x98" => "~", "\x99" => "(TM)", "\x9A" => "s", "\x9B" => ">",
"\x9C" => "oe", "\x9D" => " ", "\x9E" => "z", "\x9F" => "Y"));

ajitsingh4u at gmail dot com (2007-08-06 07:36:40)

/**
* Replaces special characters with single quote,double quote and comma for charset iso-8859-1
*
* replaceSpecialChars()
* @param string $str
* @return string
*/
function replaceSpecialChars($str)
{
//`(96) ’(130) ?(132) ‘(145) ’(146) “(147) ”(148) ?(180) // equivalent ascii values of these characters.
$str = strtr($str, "`’?‘’?", "'','''");
$str = strtr($str, '“”', '""');
return $str;
}

peter dot goodman at gmail dot com (2007-06-28 08:17:39)

To the previous comment: great function, one character mapping it is missing is though is:
chr(226) => '?'

horak.jan AT centrum.cz (2007-05-22 07:11:16)

Here is a function to convert middle-european windows charset (cp1250) to the charset, that php script is written in:

<?php
    function cp1250_to_utf2($text){
        $dict  = array(chr(225) => 'á', chr(228) =>  '?', chr(232) => '?', chr(239) => '?', 
            chr(233) => 'é', chr(236) => 'ě', chr(237) => 'í', chr(229) => '?', chr(229) => '?', 
            chr(242) => 'ň', chr(244) => '?', chr(243) => 'ó', chr(154) => '?', chr(248) => '?', 
            chr(250) => 'ú', chr(249) => '?', chr(157) => '?', chr(253) => '?', chr(158) => '?',
            chr(193) => '?', chr(196) => '?', chr(200) => '?', chr(207) => '?', chr(201) => '?', 
            chr(204) => '?', chr(205) => '?', chr(197) => '?',    chr(188) => '?', chr(210) => '?', 
            chr(212) => '?', chr(211) => '?', chr(138) => '?', chr(216) => '?', chr(218) => '?', 
            chr(217) => '?', chr(141) => '?', chr(221) => '?', chr(142) => '?', 
            chr(150) => '-');
        return strtr($text, $dict);
    }
?>

joeldegan AT yahoo (2006-04-07 08:49:50)

After battling with strtr trying to strip out MS word formatting from things pasted into forms I ended up coming up with this..

it strips ALL non-standard ascii characters, preserving html codes and such, but gets rid of all the characters that refuse to show in firefox.

If you look at this page in firefox you will see a ton of "question mark" characters and so it is not possible to copy and paste those to remove them from strings..  (this fixes that issue nicely, though I admit it could be done a bit better)

<?
function fixoutput($str){
    $good[] = 9;  #tab
    $good[] = 10; #nl
    $good[] = 13; #cr
    for($a=32;$a<127;$a++){
        $good[] = $a;
    }    
    $len = strlen($str);
    for($b=0;$b < $len+1; $b++){
        if(in_array(ord($str[$b]), $good)){
            $newstr .= $str[$b];
        }//fi
    }//rof
    return $newstr;
}
?>

martin[dot]pelikan[at]gmail[dot]com (2005-12-29 07:20:45)

// if you are upset with windows' ^M characters at the end of the line,
// these two lines are for you:
$trans = array("\x0D" => "");
$text = strtr($orig_text,$trans);
// note that ctrl+M (in vim known as ^M) is hexadecimally 0x0D

tomhmambo at seznam dot cz (2005-12-20 02:54:29)

<?
// Windows-1250 to ASCII
// This function replace all Windows-1250 accent characters with 
// thier non-accent ekvivalents. Useful for Czech and Slovak languages.

function win2ascii($str)    {    

    $str = StrTr($str,
        "\xE1\xE8\xEF\xEC\xE9\xED\xF2",
        "\x61\x63\x64\x65\x65\x69\x6E");
        
    $str = StrTr($str,
        "\xF3\xF8\x9A\x9D\xF9\xFA\xFD\x9E\xF4\xBC\xBE",
        "\x6F\x72\x73\x74\x75\x75\x79\x7A\x6F\x4C\x6C");
        
    $str = StrTr($str,
        "\xC1\xC8\xCF\xCC\xC9\xCD\xC2\xD3\xD8",
        "\x41\x43\x44\x45\x45\x49\x4E\x4F\x52");
        
    $str = StrTr($str,
        "\x8A\x8D\xDA\xDD\x8E\xD2\xD9\xEF\xCF",
        "\x53\x54\x55\x59\x5A\x4E\x55\x64\x44");

    return $str;
}
?>

Ezbakhe Yassin <yassin88 at gmail dot com> (2005-08-31 15:55:09)

Here you are a simple function to rotate a variable according to an array of possible values. You can make a strict comparison (===).

<?php
function rotateValue($string, $values, $strict = TRUE)
{
    if (!empty($string) AND is_array($values))
    {
        $valuesCount = count($values);

        for ($i = 0; $i < $valuesCount; $i++)
        {
            if ($strict ? ($string === $values[$i]) : ($string == $values[$i]))
            {
                return $values[($i + 1) % $valuesCount];
            }
        }
    }

    return FALSE;
}
?>

For example:

- rotateValue("A", array("A", "B", "C")) will return "B"
- rotateValue("C", array("A", "B", "C")) will return "A"

ru dot dy at gmx dot net (2005-07-10 16:20:47)

Posting umlaute here resulted in a mess. Heres a version of the same function that works with preg_replace only:
<?php
  function getRewriteString($sString) {
     $string = strtolower(htmlentities($sString));
     $string = preg_replace("/&(.)(uml);/", "$1e", $string);
     $string = preg_replace("/&(.)(acute|cedil|circ|ring|tilde|uml);/", "$1", $string);
     $string = preg_replace("/([^a-z0-9]+)/", "-", html_entity_decode($string));
     $string = trim($string, "-");
     return $string;
  }
?>

-sven (www.bitcetera.com) (2005-04-20 23:48:11)

And while we're at it, yet another transcriber (the code formerly known as accent remover). It does accents and umlauts, but also ligatures and runes known to ISO-8859-1. The translation strings must be on one line without any whitespaces in it. They are rendered hardwrapped here because this documentation doesn't allow long lines in notes.
function transcribe($string) {
$string = strtr($string,
"\xA1\xAA\xBA\xBF\xC0\xC1\xC2\xC3\xC5\xC7
\xC8\xC9\xCA\xCB\xCC\xCD\xCE\xCF\xD0\xD1
\xD2\xD3\xD4\xD5\xD8\xD9\xDA\xDB\xDD\xE0
\xE1\xE2\xE3\xE5\xE7\xE8\xE9\xEA\xEB\xEC
\xED\xEE\xEF\xF0\xF1\xF2\xF3\xF4\xF5\xF8
\xF9\xFA\xFB\xFD\xFF",
"!ao?AAAAAC
EEEEIIIIDN
OOOOOUUUYa
aaaaceeeei
iiidnooooo
uuuyy");
$string = strtr($string, array("\xC4"=>"Ae", "\xC6"=>"AE", "\xD6"=>"Oe", "\xDC"=>"Ue", "\xDE"=>"TH", "\xDF"=>"ss", "\xE4"=>"ae", "\xE6"=>"ae", "\xF6"=>"oe", "\xFC"=>"ue", "\xFE"=>"th"));
return($string);
}
(Funky: ISO-8859-1 does not cover the french "oe" ligature.)

info at oscaralexander dot com (2005-04-13 00:32:36)

Here's a nice function for parsing a string to something suitable for URL rewriting (mod_rewrite). It translates all accented characters to their non-accented equivalents and replaces all other non-alphanumeric character with dashes:
function getRewriteString($sString) {
$string = htmlentities(strtolower($string));
$string = preg_replace("/&(.)(acute|cedil|circ|ring|tilde|uml);/", "$1", $string);
$string = preg_replace("/([^a-z0-9]+)/", "-", html_entity_decode($string));
$string = trim($string, "-");
return $string;
}

Stian (2005-03-02 13:58:05)

elonen at iki dot fi (2005-02-25 12:24:39)

Yet another accent remover, this time pretty complete and without any 8-bit characters in the script itself:
$txt = strtr($txt,
"\xe1\xc1\xe0\xc0\xe2\xc2\xe4\xc4\xe3\xc3\xe5\xc5".
"\xaa\xe7\xc7\xe9\xc9\xe8\xc8\xea\xca\xeb\xcb\xed".
"\xcd\xec\xcc\xee\xce\xef\xcf\xf1\xd1\xf3\xd3\xf2".
"\xd2\xf4\xd4\xf6\xd6\xf5\xd5\x8\xd8\xba\xf0\xfa".
"\xda\xf9\xd9\xfb\xdb\xfc\xdc\xfd\xdd\xff\xe6\xc6\xdf",
"aAaAaAaAaAaAacCeEeEeEeEiIiIiIiInNoOoOoOoOoOoOoouUuUuUuUyYyaAs");

patrick at p-roocks dot de (2005-02-06 14:31:18)

As Daijoubu suggested use str_replace instead of this function for large arrays/subjects. I just tried it with a array of 60 elements, a string with 8KB length, and the execution time of str_replace was faster at factor 20!
Patrick

Daijoubu (2005-01-12 03:19:32)

Wouldn't:
<?php
$s = str_replace(array_key($replace_array), array_value($replace_array), $s);
?>
be faster?
Perhaps even faster using 2 seperate arrays...

(2004-12-11 05:20:03)

If you are going to call strtr a lot, consider using str_replace instead, as it is much faster. I cut execution time in half just by doing this.

<?
// i.e. instead of:
$s=strtr($s,$replace_array);

// use: 
foreach($replace_array as $key=>$value) $s=str_replace($key,$value,$s);
?>

oliver at modix dot de (2004-10-22 01:08:00)

Replace control characters in a binary string:
<?

function cc_replace($in) {
        for ($i = 0; $i <= 31; $i++) {
                $from  .= chr($i);
                $to    .= ".";
        }
        return strtr($in, $from, $to);
}

?>

ktogias at math dot upatras dot gr (2004-09-23 03:32:42)

from-php-net dot ticket at raf256 dot com (2004-06-04 16:59:13)

Hi, before I found strtr() function I quickly wrote own repleacement, if someone is interested,
// by http://www.raf256.com - Rafal Maj
function ConvCharset($from,$to,$s) {
$l=strlen($s);
$S=''; // out put
for ($i=0; $i<$l; $i++) {
$c=$s[$i]; // curr char
$x=strpos($from, $c);
if ($x!==FALSE) $c=$to[$x];
$S.=$c;
}
return $S;
}

volkris at tamu dot edu (2004-03-19 06:25:35)

Regarding christophe's conversion, note that the \x## values should be in double quotes, not single, so that the escape will be applied.

stewey at ambitious dot ca (2004-03-04 18:11:17)

This version of macRomanToIso (originally posted by: marcus at synchromedia dot co dot uk) offers a couple of improvements. First, it removes the extra slashes '\' that broke the original function. Second, it adds four quote characters not supported in ISO 8859-1. These are the left double quote, right double quote, left single quote and right single quote.

Be sure to remove the line breaks from the two strings going into strtr or this function will not work properly.

Be careful what text you apply this to. If you apply it to ISO 8859-1 encoded text it will likely wreak havoc. I'll save you some trouble with this bit of advice: don't bother trying to detect what charset a certain text file is using, it can't be done reliably. Instead, consider making assumptions based upon the HTTP_USER_AGENT, or prompting the user to specify the character encoding used (perhaps both).

<?php

/**
 * Converts MAC OS ROMAN encoded strings to the ISO 8859-1 charset.
 *
 * @param    string    the string to convert.
 * @return    string    the converted string.
 */
function macRomanToIso($string)
{
    return strtr($string,
"\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b
\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97
\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa1\xa4\xa6\xa7
\xa8\xab\xac\xae\xaf\xb4\xbb\xbc\xbe\xbf\xc0\xc1
\xc2\xc7\xc8\xca\xcb\xcc\xd6\xd8\xdb\xe1\xe5\xe6
\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf1\xf2\xf3
\xf4\xf8\xfc\xd2\xd3\xd4\xd5",
"\xc4\xc5\xc7\xc9\xd1\xd6\xdc\xe1\xe0\xe2\xe4\xe3
\xe5\xe7\xe9\xe8\xea\xeb\xed\xec\xee\xef\xf1\xf3
\xf2\xf4\xf6\xf5\xfa\xf9\xfb\xfc\xb0\xa7\xb6\xdf\xae
\xb4\xa8\xc6\xd8\xa5\xaa\xba\xe6\xf8\xbf\xa1\xac
\xab\xbb\xa0\xc0\xc3\xf7\xff\xa4\xb7\xc2\xca\xc1
\xcb\xc8\xcd\xce\xcf\xcc\xd3\xd4\xd2\xda\xdb\xd9
\xaf\xb8\x22\x22\x27\x27");
}

?>

christophe at publicityweb dot com (2004-02-26 12:04:59)

Latin1 (iso-8859-1) DONT define chars \x80-\x9f (128-159),
but Windows charset 1252 defines _some_ of them
-- like the infamous msoffice 'magic quotes' (\x92 146).
Dont use those invalid control chars in webpages,
but their html (unicode) entities. See ftp.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WINDOWS/CP1252.TXT
or http://www.microsoft.com/typography/unicode/1252.htm
PS: a '?' in the code means the win-cp1252 dont define the given char.
$badlatin1_cp1252_to_htmlent =
array(
'\x80'=>'&#x20AC;', '\x81'=>'?', '\x82'=>'&#x201A;', '\x83'=>'&#x0192;',
'\x84'=>'&#x201E;', '\x85'=>'&#x2026;', '\x86'=>'&#x2020;', \x87'=>'&#x2021;',
'\x88'=>'&#x02C6;', '\x89'=>'&#x2030;', '\x8A'=>'&#x0160;', '\x8B'=>'&#x2039;',
'\x8C'=>'&#x0152;', '\x8D'=>'?', '\x8E'=>'&#x017D;', '\x8F'=>'?',
'\x90'=>'?', '\x91'=>'&#x2018;', '\x92'=>'&#x2019;', '\x93'=>'&#x201C;',
'\x94'=>'&#x201D;', '\x95'=>'&#x2022;', '\x96'=>'&#x2013;', '\x97'=>'&#x2014;',
'\x98'=>'&#x02DC;', '\x99'=>'&#x2122;', '\x9A'=>'&#x0161;', '\x9B'=>'&#x203A;',
'\x9C'=>'&#x0153;', '\x9D'=>'?', '\x9E'=>'&#x017E;', '\x9F'=>'&#x0178;'
);
$str = strtr($str, $badlatin1_cp1252_to_htmlent);

rortiz_reyes at hotmail dot com (2004-01-26 21:15:46)

j at pureftpd dot org (2003-11-30 08:24:56)

Here's a very useful function to translate Microsoft characters into Latin 15, so that people won't see any more square instead of characters in web pages .
function demicrosoftize($str) {
return strtr($str,
"\x82\x83\x84\x85\x86\x87\x89\x8a" .
"\x8b\x8c\x8e\x91\x92\x93\x94\x95" .
"\x96\x97\x98\x99\x9a\x9b\x9c\x9e\x9f",
"'f\".**^\xa6<\xbc\xb4''" .
"\"\"---~ \xa8>\xbd\xb8\xbe");
}

Fernando "Malk" Piancastelli (2003-10-29 13:31:58)

Here's a function to replace linebreaks to html <p> tags. This was initially designed to receive a typed text by a form in a "insert new notice" page and put in a database, then a "notice" page could get the text preformatted with paragraph tags instead of linebreaks that won't appear on browser. The function also removes repeated linebreaks the user may have typed in the form.
function break_to_tags(&$text) {
// find and remove repeated linebreaks
$double_break = array("\r\n\r\n" => "\r\n");
do {
$text = strtr($text, $double_break);
$position = strpos($text, "\r\n\r\n");
} while ($position !== false);
// find and replace remanescent linebreaks by <p> tags
$change = array("\r\n" => "<p>");
$text = strtr($text, $change);
}
[]'s
Fernando

Sanate at seznam dot cz (2003-07-17 05:51:12)

// Hello to all Czech and Slovak people!
// I hope this function can be useful and easier to find here,
// than at the original source (and opposite direction). :
// http://www.kosek.cz/clanky/tipy/qa07.html
// s pozdravem Filip Rydlo z Pohodasoftware.Cz
function latin2_to_win1250($text) { // chce text v iso-88592
$text = StrTr($text, "\xA\xAB\xAE\xB\xBB\xBE",
"\x8A\x8D\x8E\x9A\x9D\x9E");
return $text;
}

mykel at has dot it (2003-02-05 18:08:20)

strtr is a usefull encoding mechinism instead of using str_rot13. you can impliment it when you write usernames to a file, for example. but know that it is easy to crack your encription.
an example:
<?php
$unencripted = "hello";
$from = "abcdefghijklmnopqrstuvwxyz";
$to =    "zyxwvutsrqponmlkjihgfedcba";
$temp = strtr($unencripted, $from, $to);
/* will return svool */
?>

hotmail - marksteward (2002-11-26 19:39:26)

m dot frank at beam dot ag (2002-11-22 05:12:37)

to get the ascii equivalent of unicode characters simply use the

utf8_decode() function

marco dot colombo at nexor dot it (2002-11-12 06:20:21)

Suppose you're trying to remove any character not in your set, i've found this very helpfull:
function my_remove($string, $my_set, $new=" ", $black="#")
{
$first = strtr( $string, $my_set,
str_repeat($black, strlen($my_set)) );
$second = strtr( $string, $first,
str_repeat($new, strlen($first)) );
return $second;
};
NOTE that all non-wanted character will be replace with $new,
note also that $black must NOT to exist in $my_set.
Molok

bisqwit at iki dot fi (2002-08-10 10:18:20)

#!/bin/sh
# This shell script generates a strtr() call
# to translate from a character set to another.
# Requires: gnu recode, perl, php commandline binary
#
# Usage:
#  Set set1 and set2 to whatever you prefer
#  (multibyte character sets are not supported)
#  and run the script. The script outputs
#  a strtr() php code for you to use.
#
# Example is set to generate a
# cp437..latin9 conversion code.
#
set1=cp437
set2=iso-8859-15
result="`echo '<? for($c=32;$c<256;$c++)'\
              'echo chr($c);'\            
         |php -q|recode -f $set1..$set2`"
echo "// This php function call converts \$string in $set1 to $set2";
cat <<EOF  | php -q
<?php
\$set1='`echo -n "$result"\
   |perl -pe "s/([\\\\\'])/\\\\\\\\\\$1/g"`';
\$set2='`echo -n "$result"|recode -f $set2..$set1\
   |perl -pe "s/([\\\\\'])/\\\\\\\\\\$1/g"`';
\$erase=array();
\$l=strlen(\$set1);
for(\$c=0;\$c<\$l;++\$c)
  if(\$set1[\$c]==\$set2[\$c])\$erase[\$set1[\$c]]='';
if(count(\$erase))
{
  \$set1=strtr(\$set1,\$erase);
  \$set2=strtr(\$set2,\$erase);
}
if(!strlen(\$set1))echo 'IRREVERSIBLE';else
echo "strtr(\\\$string,\n  '",
     ereg_replace('([\\\\\\'])', '\\\\\\1', \$set2),
     "',\n  '",
     ereg_replace('([\\\\\\'])', '\\\\\\1', \$set1),
     "');";
EOF

gabi at unica dot edu (2002-07-17 05:32:10)

symlink23-remove-my-spleen at yahoo dot com (2002-04-18 21:33:11)

As noted in the str_rot13 docs, some servers don't provide the str_rot13() function. However, the presence of strtr makes it easy to build your own facsimile thereof:
if (!function_exists('str_rot13')) {
function str_rot13($str) {
$from = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$to = 'nopqrstuvwxyzabcdefghijklmNOPQRSTUVWXYZABCDEFGHIJKLM';
return strtr($str, $from, $to);
}
}
This is suitable for very light "encryption" such as hiding email addressess from spambots (then unscrambling them in a mail class, for example).
$mail_to=str_rot13("$mail_to");

erik at eldata dot se (2001-11-23 09:08:00)

As an alternative to the not-yet-existing function stritr mentioned in the first note above You can easily do this:
strtr("abc","ABCabc","xyzxyz")
or more general:
strtr("abc",
strtoupper($fromchars).strtolower($fromchars),
$tochars.$tochars);
Just a thought.