在网络上找到的程序,如下:

<?php
class Segmentation {
   var $options = array('lowercase' => TRUE,
                        'segment_english' => FALSE);
   var $dict_name = 'Unknown';
   var $dict_words = array();
   function setLowercase($value) {
       if ($value) {
           $this->options['lowercase'] = TRUE;
       } else {
           $this->options['lowercase'] = FALSE;
       }
       return TRUE;
   }

   function setSegmentEnglish($value) {
       if ($value) {
           $this->options['segment_english'] = TRUE;
       } else {
           $this->options['segment_english'] = FALSE;
       }
       return TRUE;
   }
   function load($dict_file) {
       if (!file_exists($dict_file)) {
           return FALSE;
       }
       $fp = fopen($dict_file, 'r');
       $temp = fgets($fp, 1024);
       if ($temp === FALSE) {
           return FALSE;
       } else {
           if (strpos($temp, "t") !== FALSE) {
               list ($dict_type, $dict_name) = explode("t", trim($temp));
           } else {
               $dict_type = trim($temp);
               $dict_name = 'Unknown';
           }
           $this->dict_name = $dict_name;
           if ($dict_type !== 'DICT_WORD_W') {
               return FALSE;
           }
       }
       while (!feof($fp)) {
           $this->dict_words[rtrim(fgets($fp, 32))] = 1;
       }
       fclose($fp);
       return TRUE;
   }
   function getDictName() {
       return $this->dict_name;
   }
   function segmentString($str) {
       if (count($this->dict_words) === 0) {
           return FALSE;
       }
       $lines = explode("n", $str);
       return $this->_segmentLines($lines);
   }
   function segmentFile($filename) {
       if (count($this->dict_words) === 0) {
           return FALSE;
       }
       $lines = file($filename);
       return $this->_segmentLines($lines);
   }
   function _segmentLines($lines) {
       $contents_segmented = '';
       foreach ($lines as $line) {
           $contents_segmented .= $this->_segmentLine(rtrim($line)) . " n";
       }
       do {
           $contents_segmented = str_replace('  ', ' ', $contents_segmented);
       } while (strpos($contents_segmented, '  ') !== FALSE);
       return $contents_segmented;
   }
   function _segmentLine($str) {
       $str_final = '';
       $str_array = array();
       $str_length = strlen($str);
       if ($str_length > 0) {
           if (ord($str{$str_length-1}) >= 129) {
               $str .= ' ';
           }
       }
       for ($i=0; $i<$str_length; $i++) {
           if (ord($str{$i}) >= 129) {
               $str_array[] = $str{$i} . $str{$i+1};
               $i++;
           } else {
               $str_tmp = $str{$i};
               for ($j=$i+1; $j<$str_length; $j++) {
                   if (ord($str{$j}) < 129) {
                       $str_tmp .= $str{$j};
                   } else {
                       break;
                   }
               }
               $str_array[] = array($str_tmp);
               $i = $j - 1;
           }
       }
 
       $pos = count($str_array);
       while ($pos > 0) {
           $char = $str_array[$pos-1];
           if (is_array($char)) {
               $str_final_tmp = $char[0];
               if ($this->options['segment_english']) {
                   $str_final_tmp = preg_replace("/([!"#$%&'()*+,-./:;
<=>?@[\\]^_`{|}~tf]+)/", " $1 ", $str_final_tmp);
                   $str_final_tmp = preg_replace("/([!"#$%&'()*+,-./:;
<=>?@[\\]^_`{|}~tf])([!"#$%&'()*+,-./:;<=>?@[\\]^_`
{|}~tf])/", " $1 $2 ", $str_final_tmp);
               }
               if ($this->options['lowercase']) {
                   $str_final_tmp = strtolower($str_final_tmp);
               }
               $str_final = " $str_final_tmp$str_final";
               $pos--;
           } else {
               $word_found = 0;
               $word_array = array(0 => '');
               if ($pos < 4) {
                   $word_temp = $pos + 1;
               } else {
                   $word_temp = 5;
               }
               for ($i=1; $i<$word_temp; $i++) {
                   $word_array[$i] = $str_array[$pos-$i] . $word_array[$i-1];
               }
 
               for ($i=($word_temp-1); $i>1; $i--) {
 
                   if (array_key_exists($word_array[$i], $this->dict_words)) {
                      $word_found = $i;
                      break;
                   }
               }
               if ($word_found) {
                   $str_final = " $word_array[$word_found]$str_final";
                   $pos = $pos - $word_found;
               } else {
                   $str_final = " $char$str_final";
                   $pos--;
               }
           }
       }
       return $str_final;
   }
}
?>
来源参考：
http://www.phpchina.cn/code/2006/0607/381.html
http://www.xuchao.cn/?play=reply&id=851