Zero Size Files - Computerphile

TL;DR

When creating an empty text document, it appears to have zero bytes, but there is actually some information stored alongside it in the file description.

Transcript

One of our loyal viewers sent in a question the other day. He was asking why, when he creates an empty text document on his computer, does it have a file size of zero bytes. Well, there's no text in it, so that sort of makes sense, but he realized - well, actually, there's some information associated with it, this thing - it's got a file name, ther... Read More

Key Insights

• 📁 Empty text documents appear to have zero bytes, but they have associated file descriptions that store information about the file.
• 📁 The file system, such as FAT, divides the disk into tracks and sectors to store both data and the directory/catalog.
• 📁 The directory entry for a file contains details like the file name, extension, size, and starting cluster.
• 📁 The file description and the document itself are separate entities, allowing for file renaming without modifying the content.

Questions & Answers

Q: Why does an empty text document have zero bytes?

An empty text document appears to have zero bytes because it does not contain any text content. However, it does have information stored in its file description.

Q: Where is the information about the file name, size, and creation time stored?

This information is stored in the directory or catalog of the file system. In the FAT system, for example, each file's information is stored in 32-byte entries.

Q: What happens when you rename a file?

When you rename a file, the document itself remains unchanged. Only the file's name in its description is modified. The document retains the same data.

Q: Can empty files take up disk space?

Empty files do not take up disk space because all the necessary information is stored in the file description within the file system. However, when the directory's cluster is full, the next empty file will require additional disk space.

Summary & Key Takeaways

• Empty text documents appear to have zero bytes, but they contain information such as the file name, size, and creation time.

• The actual content of a document is separate from its description, which includes information about the document.

• File systems, like the FAT system, store this information in a directory or catalog that represents where the data is stored.