memory problems

This is a great class, but please help me to solve the memory allocation problem. In example:
When i have a 16815544 bytes large file, and
ini_set('memory_limit', '8M');
applied, the result is:
Allowed memory size of 8388608 bytes exhausted (tried to allocate 7415129 bytes) in /split_merge.inc.php on line 40

Sorry i couldn't answer sooner, this class puts the file content in memory in spliting and mergin process so it won't be able to handle big files with a limited memory. The only solution is to increase the memory allocated to php. I can't think of any other solution for handling big files.

the merge method could be rewritten to

/*------------------------------------------------------------------
- MERGE -
- This function merges splited files that are splited with above -
- split_file function. -
--------------------------------------------------------------------*/
function merge_file($merged_file_name,$parts_num)
{
$content='';
//put splited files content into content
$mhandle=fopen($merged_file_name, 'wb') or die("error creating/opening merged file");
for($i=0;$i<$parts_num;$i++)
{
$file_size = filesize('splited_'.$i);
$handle = fopen('splited_'.$i, 'rb') or die("error opening file");
$content = fread($handle, $file_size) or die("error reading file");
fclose($handle);
//write content to merged file
fwrite($mhandle, $content) or die("error writing to merged file");
}
fclose($mhandle);
return 'OK';
}//end of function merge_file