[ethan42]

Updates chapter 10 for the 2026-27 lecture 10 slides (assets/pdf/lec10.pdf on the course site). The new slides URL goes live when progintro.github.io#45 is merged.

The deck has the same 53 pages, and no page numbers moved. The only content change is on p. 2. That page was empty in 2025-26 and now asks two questions:

• «Ποια η διαφορά (υπάρχει;) μιας συνάρτησης και ενός προγράμματος;»
• «Ποια η διαφορά (υπάρχει;) ανάμεσα στην τιμή επιστροφής μιας συνάρτησης και τον κωδικό εξόδου ενός προγράμματος;»

Besides that, pp. 3–4 add painting captions and the closing slide is reworded.

Changes:

• Chapter 10: a paragraph at the end of the Σύνοψη answers both questions briefly. The slides give no answer.
  • Function vs program: who calls it (other code vs the operating system), and arguments of any type vs text through argc/argv.
  • Return value vs exit code: the exit code is main's return value, but the shell sees only 0–255 (echo $?). It links to chapter 3.
    The reading list points to the new deck, cites p. 2 and links to the 2025-26 deck (same page numbers).
• Fourteen slide questions: they point to the new deck, with page numbers unchanged.
• Other files: sources/extract/lec10.yaml (year, slides, p. 2 outline, and an issue describing the changes), the manifest, make fetch, and the README line «Διαλέξεις 0–10».

make check passes.

Opened from socrates.