Imperative Programming Constructs Flashcards

In a Picat `if-then-else` expression, what is required if the else branch is omitted?

Answer: Omitting else is a syntax error in function mode

In Picat's functional/imperative mode, if without else is a syntax error; both branches must be present.

How are multi-dimensional arrays indexed in Picat?

Answer: A[I,J]

Picat uses comma-separated indices inside a single bracket pair, e.g., A[I,J], for multi-dimensional array access.

What built-in predicate fills an array with a default value in Picat?

Answer: There is no fill built-in; use a foreach loop to initialize

Picat allocates arrays with new_array but does not have a fill built-in; initialization requires iterating and assigning each element.

Which statement about `return` in a Picat function is correct?

Answer: return Expr exits the function with value Expr

Picat supports the return Expr statement to exit a function early and produce a return value.

In Picat, how is standard output written from an imperative function?

Answer: Both print(X) and printf(Fmt,Args) are valid

Picat provides both print/println for simple output and printf/writef for formatted output in imperative functions.

What does `new_array(5)` produce in Picat?

Answer: A 1-D array of size 5 with uninitialized (free) elements

new_array(5) creates a one-dimensional array of 5 elements, each an unbound (free) variable.

How do you iterate over both index and value of a list in a Picat `foreach` loop?

Answer: foreach(I in 1..List.len, V = List[I])

The standard idiom is to iterate over an index range and access List[I], since foreach over a list gives values only.