PHP: get remote file size with strlen? (html)

Question

I was looking at PHP docs for fsockopen and whatnot and they say you can\'t use filesize() on a remote file without doing some crazy things with ftell or something (not sure

Answer 1

it will fetch the whole file and then calculate the filesize (rather the string length) out of the retrieved data. usually filesize can tell the filesize directly from the filesystem without reading the whole file first.

so this will be rather slow, and will everytime fetch the whole file before being able to retrieve the filesize (string length