Question

I understand content length to be the size of an object in byte e.g. 1 byte or 1024bytes, etc however what is data length? Not sure whether it is language specific but if it is I would like to know how it applies to PHP and ASP.NET

Answer 1

For object size you can use memory_get_usage() as per the linked answer.

For file size you can use filesize();

EIDT: in line with updated query.

As per your comment on the question you’d be looking for filesize(), I think.

• File size is the amount of space on a storage device which is occupied by a given flie.
• Object size is the amount of RAM that the object consumes while it is
  instantiated.

Imagine a sheet of paper with ten numbers on it and enough space to write another ten or so. As long as you don’t edit the text on the sheet of paper its contents will remain the same regardless of whether or not you can see or even interact with the sheet of paper.

Now imagine you need three of these numbers for a task, you’ve (as an example) the capacity to remember a sequence of up to five numbers, so you memorise the sequence. Once you’ve carried out the task you required the sequence for it can be discarded from (your) memory to free up space. Once the sequence has been freed from memory (object destroyed) you will no longer be able to recollect it or similarly if you experience an unexpected life exception, say knock yourself out and you forgot the sequence, the sheet of paper does not.