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Auto language selection

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Auto language selection based on site languages and user preferences.

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  1. <?php
  2. /* 
  3.   determine which language out of an available set the user prefers most
  4.   
  5.   $available_languages        array with language-tag-strings (must be lowercase) that are available
  6.   $http_accept_language    a HTTP_ACCEPT_LANGUAGE string (read from $_SERVER['HTTP_ACCEPT_LANGUAGE'] if left out)
  7. */
  8. function prefered_language ($available_languages,$http_accept_language="auto") {
  9.     // if $http_accept_language was left out, read it from the HTTP-Header
  10.     if ($http_accept_language == "auto") $http_accept_language = $_SERVER['HTTP_ACCEPT_LANGUAGE'];
  11.  
  12.     // standard  for HTTP_ACCEPT_LANGUAGE is defined under 
  13.     // http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.4
  14.     // pattern to find is therefore something like this:
  15.     //    1#( language-range [ ";" "q" "=" qvalue ] )
  16.     // where:
  17.     //    language-range  = ( ( 1*8ALPHA *( "-" 1*8ALPHA ) ) | "*" )
  18.     //    qvalue         = ( "0" [ "." 0*3DIGIT ] )
  19.     //            | ( "1" [ "." 0*3("0") ] )
  20.     preg_match_all("/([[:alpha:]]{1,8})(-([[:alpha:]|-]{1,8}))?" . 
  21.                    "(\s*;\s*q\s*=\s*(1\.0{0,3}|0\.\d{0,3}))?\s*(,|$)/i", 
  22.                    $http_accept_language, $hits, PREG_SET_ORDER);
  23.  
  24.     // default language (in case of no hits) is the first in the array
  25.     $bestlang = $available_languages[0];
  26.     $bestqval = 0;
  27.  
  28.     foreach ($hits as $arr) {
  29.         // read data from the array of this hit
  30.         $langprefix = strtolower ($arr[1]);
  31.         if (!empty($arr[3])) {
  32.             $langrange = strtolower ($arr[3]);
  33.             $language = $langprefix . "-" . $langrange;
  34.         }
  35.         else $language = $langprefix;
  36.         $qvalue = 1.0;
  37.         if (!empty($arr[5])) $qvalue = floatval($arr[5]);
  38.  
  39.         // find q-maximal language  
  40.         if (in_array($language,$available_languages) && ($qvalue > $bestqval)) {
  41.             $bestlang = $language;
  42.             $bestqval = $qvalue;
  43.         }
  44.         // if no direct hit, try the prefix only but decrease q-value by 10% (as http_negotiate_language does)
  45.         else if (in_array($langprefix,$available_languages) && (($qvalue*0.9) > $bestqval)) {
  46.             $bestlang = $langprefix;
  47.             $bestqval = $qvalue*0.9;
  48.         }
  49.     }
  50.     return $bestlang;
  51. }
  52. ?>

URL: http://de2.php.net/manual/en/function.http-negotiate-language.php#

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