Icon Analyst 52 -- Supplementary Material
Last updated January 22, 1999
Answers to Quiz on Structures
1. False. L[0] is an attempt to reference an element beyond the end of L, which fails.
2. True.
3. They both produce the same results, but the first leaves L unchanged, while the second removes all its elements, leaving it empty.
4. It adds a null-valued element to the right end of L.
5. They all leave L unchanged, although some differ in intermediate steps.
6. L := sort(set(L)).
7. True.
8. False.
9. False.
10. False. If R has a field named center, they produce the same results, but if R doesn’t have a field named center, R.center causes a run-time error, while R["center"] fails.
11. True.
12. True.
13. False.
14. False; the order is unpredictable but not random.
15. *sort(S).
16.
procedure elim_str(S)
every x := !S do
if type(x) == "string" then delete(S, x)
return S
end
17. set(R), set(S), set(T), and list(S) cause run-time errors. table(S) creates a table whose default value is S.18. True.
19. False in general.
20.
procedure keyset(T) S := set() every insert(S, keys(T)) return S end
21. Values can be obtained from keys, as in
T[key(T)]. The converse is not true.22. True, although this is a property of the implementation and not specified in the language.
23. False. Although there is no language or implementation limit on the number of elements in a table, it must fit in memory, which is limited.
Graphics Corner -- Transparency
Figure 1. The Affect of Transparency
Figure 2. Unicorn Silhouette
Figure 3. A Numerical Carpet
Figure 4. Unicorn Adorned with a Carpet
Figure 5. Other Unicorn Adornments
Figure 6. The Images for Masks
Figure 7. Shuttering the Unicorn
Animation — Mutable Colors
Figure 1. Marquee Layout
Figure 2. Successive Marquee Images
Figure 3. Path Layout
Figure 4. Snapshots of the Worm
Figure 5. An Expanding Ring
Figure 6. Revolving Rotors
Figure 7. Revolving Color Wheel
From the Library -- PostScript Graphics
Figure 1. Screen Image
Figure 2. Enlarged Screen Image
Figure 3. PostScript Image
Figure 4. Enlarged PostScript
Figure 5. Pixel Rendering
