| 1) |
The following grammars define regular languages. Give a single EBNF
rule without recursion for every grammar. [5 credit points]
-
A = A a | A b | c
-
A = A a b | c
-
A = a A | A b | c
-
A = A a | B b B
B = B b | c
|
| 2) |
Find an EBNF grammar without recursion that specifies the syntax of
floating point numbers. The following numbers should be in the language
defined by your grammar: [5 credit points]
-3.1415927, 1.4e10, 127.0e-2, -0.1e-1
Integer numbers like 1, 4589 or -000335
(i.e. numbers without dots in the representation) need not be covered
by your grammar.
|
| 3) |
List all the errors in this small J0 program. For each error state
clearly why it is erroneous and whether it is a syntactic or a semantic
error. [5 credit points]
module Star {
Star[][] trek;
int[][] enterprise() {
while (false);
{ return newarray int[]("trek"); }
}
int voyager(int x, y) {
if x > y
int z = 2;
else
return enterprise()[-!y];
return !-5;
}
}
|
| 4) |
Write a small J0 module with a function
int scalarProduct(int[] xs, int[] ys, int n)
|
| 5) |
In the following module, function main is called with parameter 2.
What value does it return? [3 credit points]
module Magic {
int i;
int[] js;
int[] init() {
js = newarray int(2);
js[0] = 1;
js[1] = 2;
i = 2;
return js;
}
int foo(int[] ts, int j) {
return ts[i - 1] * j;
}
int bar() {
js[0] = 0;
return 1;
}
int main(int i) {
int[] ts;
ts = init();
i = 1;
ts[i - 1] = 7;
ts[1] = 6;
if (init()[0] | bar())
return js[i - 1] * foo(ts, ts[i - 1]);
else
return js[i] * (6 + i);
}
}
|
