CSCI 410 Mid-Term Exam [Solutions]

Fall 2004 [Somo]

Problem 1

{wcw^R | w in (0|1)^*}

or

Palindromes

(Many other answers possible).

Problem 2

S à A c A

A à O A

        | e

O à a | b

Problem 3

Problem 4

Class Main {

            public static void main(String [] args)

{

            Foo x;                          Soln: S; Type Foo undefined

            int y;

            int z;

            y = 0;

            z = 0;

if (y = = = 3) y = 10;    Soln: P; Two operators together (= =, =)

                                        or Invalid right operand

            y = z.foo ();                  Soln: S; Method call on non-reference type

            y = 345xyz;                  Soln: P; Invalid expression (2 operands

 together)

                        y = xyz345;                  Soln: S; Undefined variable ‘xyz345’

                        y = y @ z;                    Soln: L; Invalid lexeme “@”

            }

}

Problem 5

Problem 6

N à N₁ D                   {N.value = N₁.value * 10 + D.value;}

        | D                        {N.value = D.value;}

D à ‘0’                       {D.value = 0;}

        | ‘1’                      {D.value = 1;}

         .

         .

         .

       | ‘9’                       {D.value = 9;}