CS 355 TEST ONE                   Name__________________________________
Summer 2012                       Due: July 26th
ALL questions are valued at 10 points each.

(1). Show the postfix of the following expression and using a stack
show what the values would be if a=3, b=8, c=1.  (** is raise to a power)

a*a-b/(c**4**a+1)-a

(2). Why were the early versions of the BASIC programming language interpreted? 

(3). Composite data types (arrays & records) can be a problem when they are
passed as parameters or returned by functions. Why? What can the programmer
do to solve the problems of passing and returning arrays and records in Pascal,
C, and Fortran? (remember, the language may already have solved some of the
issues). 

(4). Consider the following:

procedure SWAP2 (x, y: integer);

      procedure F ( ) : integer;
          var z: integer;
      begin 
          z := x;  x := y;  return z
      end F;

begin
    y := F ( )
end SWAP2;

On the back of this page, show a diagram of activation records on the
runtime stack of the above procedures if the call to SWAP2 is made in the
main program.

(5). Rewrite the following program fragment using goto statements to explicitly
show the flow control through the loop.

     for ( int i = n; i > 0; i-- )
         if ( x != A[i] )
             break;

(6). In a language with strong typing, what advantage is offered by static
checking rather than dynamic checking? 

(7). Given the following grammer:

     <stmt> ::= <loop> | s
     <loop> ::= <repeat> | <while>
     <repeat> ::= repeat <stmt> until <exp>
     <while> ::= while <exp> do <stmt>
     <exp> ::= c1 | c2

  Draw the parse tree for the following:

     repeat while c1 do s until c2

(8). Given the following ML function:

     fun f (x,A) = if null A then 0 else s + hd A + f (s, tl A);

what is the output of f (10, [2, 3, 4, 5]);  ?

(9). Write an ML function "fourth" of 'a list -> 'a that returns the 4th
element of a list. you may assume that ALL lists passed to this function
have at least four elements.

(10). Write an ML function "max" of type int list -> int that returns the
largest element of a list of integers. don't worry about an empty list
as input.