Writing to a file. (PHP)

It's possible to ammend data within a file vs. just adding data to the beginning or the end of the file? Mean to change something in the "middle" of the file.

Thanks.

if you need to edit your best bet would be to just read the whole file to a varible...

but if you simply need to append your file in the middle you can set the file pointer to a certain spot in the file using the fseek() function