Difficulty: Medium · Puzzle 5 of 6 · Topic: Queue and Array Puzzles
Predict outputs of `first`, `next`, `num`, and `exists`.
module p5;
int aa[string];
string k;
bit ok;
initial begin
aa["b"] = 2;
aa["a"] = 1;
ok = aa.first(k);
$display("first_ok=%0d k=%s", ok, k);
ok = aa.next(k);
$display("next_ok=%0d k=%s", ok, k);
$display("num=%0d ex_c=%0d", aa.num(), aa.exists("c"));
end
endmoduleAssociative arrays iterate in index order, not insertion order.
1) Keys are `"a"` and `"b"`; lexical order gives `"a"` first.
2) `first(k)` returns 1 and sets k to `a`.
3) `next(k)` from `a` returns 1 and sets k to `b`.
4) `num()` is 2 and `exists("c")` is 0.Answer: first_ok=1 k=a, next_ok=1 k=b, num=2 ex_c=0
People often expect associative iteration to follow insertion order like many software maps.
What does `aa.next(k)` return if called once more after `k=b`?