configure ini like files in PHP

<?
///////////////////////////////////////////////////////////////////////// 
// 
//  class.INIFile.php3  -  implements  a  simple  INIFile Parser 
//  
///  Author : Mo

//
//  Description: 
// I just wandered how to sawe simple parameters not in a database but in a file
//  So starting every time from scratch isn't comfortable and I desided to write this
//  small unit for workin with ini like files
//  Some  Examples: 
// 
// $ini = new INIFile("./ini.ini");
//  //Read entire group in an associative array
// $grp = $ini->read_group("MAIN");
// //prints the variables in the group
// if ($grp)
// for(reset($grp); $key=key($grp); next($grp))
// {
//  echo "GROUP ".$key."=".$grp[$key]."<br>";
// }
// //set a variable to a value
// $ini->set_var("NEW","USER","JOHN");
//  //Save the file
// $ini->save_data();


class  INIFile {

 var $INI_FILE_NAME = "";
 var $ERROR = "";
 var $GROUPS = array();
 var $CURRENT_GROUP = "";
 
 function INIFile($inifilename="")
 {
  if(!empty($inifilename))
   if(!file_exists($inifilename)){
    $this->error("This file does not exist!");
    return;
   }
  $this->parse($inifilename);
 }


// LOAD AND SAVE FUNCTIONS
 
 function parse($inifilename)
 {
  $this->INI_FILE_NAME = $inifilename;
  $fp = fopen($inifilename, "r+");
  $contents = fread($fp, filesize($inifilename));
  $ini_data = split("\n",$contents);
  
  while(list($key, $data) = each($ini_data))
  {
   $this->parse_data($data);
  }
  
  fclose($fp);
 }
 
 function parse_data($data)
 {
  if(ereg("\[([[:alnum:]]+)\]",$data,$out))
  {
   $this->CURRENT_GROUP=$out[1];
  }
  else
  {
   $split_data = split("=", $data);
   $this->GROUPS[$this->CURRENT_GROUP][$split_data[0]]=$split_data[1];
  }
 }

 function save_data()
 {
  $fp = fopen($this->INI_FILE_NAME,"w");
  
  if(empty($fp))
  {
   $this->Error("Cannot create file $this->INI_FILE_NAME");
   return false;
  }
  
  $groups = $this->read_groups();
  $group_cnt = count($groups);
  
  for($i=0; $i<$group_cnt; $i++)
  {
   $group_name = $groups[$i];
   $res = sprintf("[%s]\n",$group_name);
   fwrite($fp, $res);
   $group = $this->read_group($group_name);
   for(reset($group); $key=key($group);next($group))
   {
    $res = sprintf("%s=%s\n",$key,$group[$key]);
    echo $res."\n";
    fwrite($fp,$res);
   }
  }
  
  fclose($fp);
 }

// FUNCTIONS FOR GROUPS
 
 //returns number of groups 
 function get_group_count()
 {
  return count($this->GROUPS);
 }
 
 //returns an array with the names of all the groups
 function read_groups()
 {
  $groups = array();
  for(reset($this->GROUPS);$key=key($this->GROUPS);next($this->GROUPS))
   $groups[]=$key;
  return $groups;
 }
 
 //checks if a group exists
 function group_exists($group_name)
 {
  $group = $this->GROUPS[$group_name];
  if (empty($group)) return false;
  else return true;
 }

 //returns an associative array of the variables in one group 
 function read_group($group)
 {
  $group_array = $this->GROUPS[$group];
  if(!empty($group_array)) 
   return $group_array;
  else 
  {
   $this->Error("Group $group does not exist");
   return false;
  }
 }
 
 //adds a new group
 function add_group($group_name)
 {
  $new_group = $this->GROUPS[$group_name];
  if(empty($new_group))
  {
   $this->GROUPS[$group_name] = array();
  }
  else $this->Error("Group $group_name exists");
 }


// FUNCTIONS FOR VARIABLES
 
 //reads a single variable from a group
 function read_var($group, $var_name)
 {
  $var_value = $this->GROUPS[$group][$var_name];
  if(!empty($var_value))
   return $var_value;
  else
  {
   $this->Error("$var_name does not exist in $group");
   return false;
  }
 }
 
 //sets a variable in a group
 function set_var($group, $var_name, $var_value)
 {
  if ($this->group_exists($group))
   $this->GROUPS[$group][$var_name]=$var_value;
 } 

// ERROR FUNCTION
   
 function Error($errmsg)
 {
  $this->ERROR = $errmsg;
  echo "Error:".$this->ERROR."<br>\n";
  return;
 }
}
?>