php替换字符串中间字符为省略号的方法

/** * Reduce a string by the middle, keeps whole words together * * @param string $string * @param int $max (default 50) * @param string $replacement (default [...]) * @return string * @author david at ethinkn dot com * @author loic at xhtml dot ne * @author arne dot hartherz at gmx dot net */function strMiddleReduceWordSensitive($string,$max=50,$rep='[...]'){  $strlen = strlen($string);  if ($strlen <= $max)    return $string;  $lengthtokeep = $max - strlen($rep);  $start = 0;  $end = 0;  if (($lengthtokeep % 2) == 0) {    $start = $lengthtokeep / 2;    $end = $start;  } else {    $start = intval($lengthtokeep / 2);    $end = $start + 1;  }  $i = $start;  $tmp_string = $string;  while ($i < $strlen) {    if (isset($tmp_string[$i]) and $tmp_string[$i] == ' ') {      $tmp_string = substr($tmp_string, 0, $i) . $rep;      $return = $tmp_string;    }    $i++;  }  $i = $end;  $tmp_string = strrev ($string);  while ($i < $strlen) {    if (isset($tmp_string[$i]) and $tmp_string[$i] == ' ') {      $tmp_string = substr($tmp_string, 0, $i);      $return .= strrev ($tmp_string);    }    $i++;  }  return $return;  return substr($string, 0, $start).$rep.substr($string, - $end);}

// example:$text = 'This is a very long test sentence, bla foo bar nothing';print strMiddleReduceWordSensitive ($text, 30) . "/n";// Returns: This is a very[...]foo bar nothing (~ 30 chrs)print strMiddleReduceWordSensitive ($text, 30, '...') . "/n";// Returns: This is a very...foo bar nothing (~ 30 chrs)