[abebe]

Dear TAs,

I have a question on the outcome of test case #7 below.

"
(* Public test case 7 : call by reference *)

let proc f (a,b,c) =
write a;
write b;
write c;
b := 5;
(a * b) + c
in
let x := 1 in
let y := 2 in
let z := 3 in
write(f <x,y,z> + y)

(* Output : prints out "1\n2\n3\n13\n" *)
"

Why is the output of "f <x,y,z> + y" 13? Shouldn't it be 10?


Thank you in advance for your response!
Dawit F. Amanu

[김도형]

Hello.

As procedure f is called by reference, f gets the location for its variable.

Assigning a value 5 in 'b' actually involves assigning a value to its location, which is bound to variable y.

Hence, after f<x,y,z>, y's value should be changed.

Thank you.