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optimizing a php function that trims strings

Answer 1

A:

For your return statement you could try:

return htmlspecialchars(trim($r));

EDIT: I tried your code as you provided it and it ran fine for me without having to use htmlspecialchars(). This is probably due to the face that in the <head> of the page the code was running on, the charset was set to UTF-8. So your options could be to set the encoding of the page like this:

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

or to use htmlspecialchars() as above.

greenie 2010-07-08 17:57:55

nope, didn't work.

andufo 2010-07-08 18:13:19

the � comes from half a unicode character and htmlspecialchars() won't help there.

hop 2010-07-08 18:15:59

I'm stumped then. Your original code worked absolutely fine for me on my localhost and in a production environment too. I can only take a guess at looking for things that might be causing the problem outside of what you originally posted.

greenie 2010-07-08 18:29:09

Answer 2

+3 A:

You should use the multibyte string functions to correctly handle unicode characters.

For example you could try using mb_strimwidth to truncate a string to a specified length.

Mark Byers 2010-07-08 17:59:46

seems like a good option, but i got the "Call to undefined function mb_strimwidth()" error msg -- and i do have PHP 5

andufo 2010-07-08 18:15:38

@andufo: You might want to see this related question regarding enabling the multibyte string functions: http://stackoverflow.com/questions/2294393/mb-substr-cant-be-used-on-php-5-2-6

Mark Byers 2010-07-08 18:23:32

You could also utilize iconv http://php.net/iconv

Eric Coleman 2010-07-09 00:28:52

Answer 3

A:

Aside from the multibyte issue, maybe you can write it shorter

function gen_string($str, $limit) {
    if ($str >= strlen($limit)) 
      return $str;
    $offset = -(strlen($str) - $limit);
    return substr($str, 0, strrpos($str, ' ', $offset)).'...';
}

It will limit the length of the string, so rather than cut it after the first word beyond the limit, it ensures that the length is never larger than the limit.

galambalazs 2010-07-08 18:05:46

this doesn't fix the character error issue =(

andufo 2010-07-08 18:15:06

Well I don't really know what can cause your problem because I use the code above in production without any problems. And we use űúőó characters :) Also I checked it right now and it's fine in my localhost. Are you sure everything is right in your server settings?

galambalazs 2010-07-08 18:20:23

Answer 4

+1 A:

You could also take a different approach and make use of the PCRE regex extension's UTF-8 capabilities (assuming your strings are UTF-8!).

function gen_string($string, $length)
{
    $str    = trim(strip_tags($string));
    $strlen = strlen(utf8_decode($str));
    // String is less than limit
    if ($strlen <= $length) return $str;
    // Shorten string, preserving whole "words" (non-whitespace)
    preg_match('/^.{'.($length-1).'}\S*/su', $str, $match);
    // Append ellipsis if needed (bytes length is OK to check)
    if (strlen($match[0]) !== strlen($str)) $match[0] .= '...';
    return $match[0];
}

salathe 2010-07-08 21:22:31

Answer 5

A:

strlen() cannot be used for UTF-8 string, because it would count also the continuation characters, which should not be counted.

You can try with the following code:

define('PREG_CLASS_UNICODE_WORD_BOUNDARY', 
  '\x{0}-\x{2F}\x{3A}-\x{40}\x{5B}-\x{60}\x{7B}-\x{A9}\x{AB}-\x{B1}\x{B4}' .
  '\x{B6}-\x{B8}\x{BB}\x{BF}\x{D7}\x{F7}\x{2C2}-\x{2C5}\x{2D2}-\x{2DF}' .
  '\x{2E5}-\x{2EB}\x{2ED}\x{2EF}-\x{2FF}\x{375}\x{37E}-\x{385}\x{387}\x{3F6}' .
  '\x{482}\x{55A}-\x{55F}\x{589}-\x{58A}\x{5BE}\x{5C0}\x{5C3}\x{5C6}' .
  '\x{5F3}-\x{60F}\x{61B}-\x{61F}\x{66A}-\x{66D}\x{6D4}\x{6DD}\x{6E9}' .
  '\x{6FD}-\x{6FE}\x{700}-\x{70F}\x{7F6}-\x{7F9}\x{830}-\x{83E}' .
  '\x{964}-\x{965}\x{970}\x{9F2}-\x{9F3}\x{9FA}-\x{9FB}\x{AF1}\x{B70}' .
  '\x{BF3}-\x{BFA}\x{C7F}\x{CF1}-\x{CF2}\x{D79}\x{DF4}\x{E3F}\x{E4F}' .
  '\x{E5A}-\x{E5B}\x{F01}-\x{F17}\x{F1A}-\x{F1F}\x{F34}\x{F36}\x{F38}' .
  '\x{F3A}-\x{F3D}\x{F85}\x{FBE}-\x{FC5}\x{FC7}-\x{FD8}\x{104A}-\x{104F}' .
  '\x{109E}-\x{109F}\x{10FB}\x{1360}-\x{1368}\x{1390}-\x{1399}\x{1400}' .
  '\x{166D}-\x{166E}\x{1680}\x{169B}-\x{169C}\x{16EB}-\x{16ED}' .
  '\x{1735}-\x{1736}\x{17B4}-\x{17B5}\x{17D4}-\x{17D6}\x{17D8}-\x{17DB}' .
  '\x{1800}-\x{180A}\x{180E}\x{1940}-\x{1945}\x{19DE}-\x{19FF}' .
  '\x{1A1E}-\x{1A1F}\x{1AA0}-\x{1AA6}\x{1AA8}-\x{1AAD}\x{1B5A}-\x{1B6A}' .
  '\x{1B74}-\x{1B7C}\x{1C3B}-\x{1C3F}\x{1C7E}-\x{1C7F}\x{1CD3}\x{1FBD}' .
  '\x{1FBF}-\x{1FC1}\x{1FCD}-\x{1FCF}\x{1FDD}-\x{1FDF}\x{1FED}-\x{1FEF}' .
  '\x{1FFD}-\x{206F}\x{207A}-\x{207E}\x{208A}-\x{208E}\x{20A0}-\x{20B8}' .
  '\x{2100}-\x{2101}\x{2103}-\x{2106}\x{2108}-\x{2109}\x{2114}' .
  '\x{2116}-\x{2118}\x{211E}-\x{2123}\x{2125}\x{2127}\x{2129}\x{212E}' .
  '\x{213A}-\x{213B}\x{2140}-\x{2144}\x{214A}-\x{214D}\x{214F}' .
  '\x{2190}-\x{244A}\x{249C}-\x{24E9}\x{2500}-\x{2775}\x{2794}-\x{2B59}' .
  '\x{2CE5}-\x{2CEA}\x{2CF9}-\x{2CFC}\x{2CFE}-\x{2CFF}\x{2E00}-\x{2E2E}' .
  '\x{2E30}-\x{3004}\x{3008}-\x{3020}\x{3030}\x{3036}-\x{3037}' .
  '\x{303D}-\x{303F}\x{309B}-\x{309C}\x{30A0}\x{30FB}\x{3190}-\x{3191}' .
  '\x{3196}-\x{319F}\x{31C0}-\x{31E3}\x{3200}-\x{321E}\x{322A}-\x{3250}' .
  '\x{3260}-\x{327F}\x{328A}-\x{32B0}\x{32C0}-\x{33FF}\x{4DC0}-\x{4DFF}' .
  '\x{A490}-\x{A4C6}\x{A4FE}-\x{A4FF}\x{A60D}-\x{A60F}\x{A673}\x{A67E}' .
  '\x{A6F2}-\x{A716}\x{A720}-\x{A721}\x{A789}-\x{A78A}\x{A828}-\x{A82B}' .
  '\x{A836}-\x{A839}\x{A874}-\x{A877}\x{A8CE}-\x{A8CF}\x{A8F8}-\x{A8FA}' .
  '\x{A92E}-\x{A92F}\x{A95F}\x{A9C1}-\x{A9CD}\x{A9DE}-\x{A9DF}' .
  '\x{AA5C}-\x{AA5F}\x{AA77}-\x{AA79}\x{AADE}-\x{AADF}\x{ABEB}' .
  '\x{D800}-\x{F8FF}\x{FB29}\x{FD3E}-\x{FD3F}\x{FDFC}-\x{FDFD}' .
  '\x{FE10}-\x{FE19}\x{FE30}-\x{FE6B}\x{FEFF}-\x{FF0F}\x{FF1A}-\x{FF20}' .
  '\x{FF3B}-\x{FF40}\x{FF5B}-\x{FF65}\x{FFE0}-\x{FFFD}');

function utf8_strlen($text) {
  if (function_exists('mb_strlen')) {
    return mb_strlen($text);
  }

  // Do not count UTF-8 continuation bytes.
  return strlen(preg_replace("/[\x80-\xBF]/", '', $text));
}

function utf8_truncate($string, $max_length, $wordsafe = FALSE, $add_ellipsis = FALSE, $min_wordsafe_length = 1) {
  $ellipsis = '';
  $max_length = max($max_length, 0);
  $min_wordsafe_length = max($min_wordsafe_length, 0);

  if (utf8_strlen($string) <= $max_length) {
    // No truncation needed, so don't add ellipsis, just return.
    return $string;
  }

  if ($add_ellipsis) {
    // Truncate ellipsis in case $max_length is small.
    $ellipsis = utf8_substr('...', 0, $max_length);
    $max_length -= utf8_strlen($ellipsis);
    $max_length = max($max_length, 0);
  }

  if ($max_length <= $min_wordsafe_length) {
    // Do not attempt word-safe if lengths are bad.
    $wordsafe = FALSE;
  }

  if ($wordsafe) {
    $matches = array();
    // Find the last word boundary, if there is one within $min_wordsafe_length
    // to $max_length characters. preg_match() is always greedy, so it will
    // find the longest string possible.
    $found = preg_match('/^(.{' . $min_wordsafe_length . ',' . $max_length . '})[' . PREG_CLASS_UNICODE_WORD_BOUNDARY . ']/u', $string, $matches);
    if ($found) {
      $string = $matches[1];
    }
    else {
      $string = utf8_substr($string, 0, $max_length);
    }
  }
  else {
    $string = utf8_substr($string, 0, $max_length);
  }

  if ($add_ellipsis) {
    $string .= $ellipsis;
  }

  return $string;
}

function utf8_substr($text, $start, $length = NULL) {
  if (function_exists('mb_substr')) {
    return $length === NULL ? mb_substr($text, $start) : mb_substr($text, $start, $length);
  }
  else {
    $strlen = strlen($text);
    // Find the starting byte offset.
    $bytes = 0;
    if ($start > 0) {
      // Count all the continuation bytes from the start until we have found
      // $start characters or the end of the string.
      $bytes = -1;
      $chars = -1;
      while ($bytes < $strlen - 1 && $chars < $start) {
        $bytes++;
        $c = ord($text[$bytes]);
        if ($c < 0x80 || $c >= 0xC0) {
          $chars++;
        }
      }
    }
    elseif ($start < 0) {
      // Count all the continuation bytes from the end until we have found
      // abs($start) characters.
      $start = abs($start);
      $bytes = $strlen;
      $chars = 0;
      while ($bytes > 0 && $chars < $start) {
        $bytes--;
        $c = ord($text[$bytes]);
        if ($c < 0x80 || $c >= 0xC0) {
          $chars++;
        }
      }
    }
    $istart = $bytes;

    // Find the ending byte offset.
    if ($length === NULL) {
      $iend = $strlen;
    }
    elseif ($length > 0) {
      // Count all the continuation bytes from the starting index until we have
      // found $length characters or reached the end of the string, then
      // backtrace one byte.
      $iend = $istart - 1;
      $chars = -1;
      $last_real = FALSE;
      while ($iend < $strlen - 1 && $chars < $length) {
        $iend++;
        $c = ord($text[$iend]);
        $last_real = FALSE;
        if ($c < 0x80 || $c >= 0xC0) {
          $chars++;
          $last_real = TRUE;
        }
      }
      // Backtrace one byte if the last character we found was a real character
      // and we don't need it.
      if ($last_real && $chars >= $length) {
        $iend--;
      }
    }
    elseif ($length < 0) {
      // Count all the continuation bytes from the end until we have found
      // abs($start) characters, then backtrace one byte.
      $length = abs($length);
      $iend = $strlen;
      $chars = 0;
      while ($iend > 0 && $chars < $length) {
        $iend--;
        $c = ord($text[$iend]);
        if ($c < 0x80 || $c >= 0xC0) {
          $chars++;
        }
      }
      // Backtrace one byte if we are not at the beginning of the string.
      if ($iend > 0) {
        $iend--;
      }
    }
    else {
      // $length == 0, return an empty string.
      return '';
    }

    return substr($text, $istart, max(0, $iend - $istart + 1));
  }
}

kiamlaluno 2010-07-08 21:47:21

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optimizing a php function that trims strings

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