Programming Languages Exam

 

Name ______________________________

 

This is a long exam.  Do not get bogged down on any question.  Do the ones you can do first.  

 

 

The total number of points you can earn on this exam is 105.

If you estimate your total earned points within 5 points of your actual earned points, I will add 5 points to your total score.  You do not have to add up your points, it is sufficient to indicate the points per page in the empty column.

 

Question Page

Max

Points Possible

Estimated

Earned Points

Actual

Earned Points

Short Answers – page 1

10

 

 

Short Answers – page 2

10

 

 

Short Answers – page 3

10

 

 

Scope Question

10

 

 

FOR LOOP

10

 

 

Grammar Question

15

 

 

Comparative Languages

15

 

 

Parameter Passing

16

 

 

Ada For Loop Question

10

 

 

 

      105

 

 

 

I have observed the provisions of the honor code in completing this exam.

 

 

_______________________

Signature

Programming Languages Exam

Short Answers  - Page 1

 

Name ____________               Max Points:   10               Points Earned:  _____

 

The three languages we have looked at thus far this semester have different approaches to the use of non-local variables.

Briefly describe how each provides access to non-local variables (if they do).

 

FORTRAN

only access is through parameter list or through common block

 

Pascal

through parameter list and any variable not declared locally which is declared in a surrounding block (an outer block)is accessible

 

Ada

through parameter list and using a with/use combination or a with statement and a fully qualified reference to a variable in another program unit.

 

 

Our book list the three most important criteria for evaluating a programming language as readabilit, writability and reliability.  Pick one of these and  list  three (3) programming language elements that affect it. 

 

Criterion: 

Readability

Writability

Reliability

Element 1

 

simplicity/orthogonality

control structures

simplicity/orthogonality

control structures

simplicity/orthogonality

control structures

Element 2

data types & structures

syntax design

data types & Structures

syntax design

data types & Structures

Element 3

syntax design

 

support for abstraction

expressivity

support for abstraction

expressivity

type checking

exception handling

restricted aliasing

 

Our text indicates four (4) basic categories of languages.  List the four (4) categories and for each,  indicate a language that  is representative of the category.

 

Category

Representative Language

imperative

Ada, FORTRAN, Pascal, C

functional

Lisp, Scheme, ML

Logic

Prolog

object oriented

C++, Java, C#, Smalltalk

Programming Languages Exam

Short Answers  - Page 2

 

Name ____________               Max Points:   10               Points Earned:  _____

 

One of the attributes of variables that  we have discussed in class is name.  Briefly and clearly  describe three (3) decisions language designers make with regard to variable names.

 

length - how long can a legal variable name be?  how many characters are relevant?

character set - what characters are allowed?  Are any required or forbidden in initial position?

case sensitivity - does case sensitivity matter?

reserved or key words -

 

 

We have discussed two types of bindings:  static  and dynamic.  Provide a definition for dynamic binding and tell where we might see an example  of a dynamically bound variable in a programming language.

 

Definition: 

a dynamic binding first orrucs during run time or can change in the course of program execution

Example:

pointer variables are dynamically bound to memory locations

objects

 

 

When this course is over and  you need to learn a new programming language, what are five (5) distinct types of statements you will expect to find in the new language.

1.  input

 

2.  output

 

3. assignment

 

4. selection

 

5. iteration

 

 

 

 

 

 

 

Programming Languages Exam

Short Answers  - Page 3

 

Name ____________               Max Points:  10                Points Earned:  _____

 

 

What is the difference between the use of the semi-colon in Pascal and Ada?

 

in Pascal:

in Pascal, the semi-colon is a statement separator

in Ada:

the semi-colon is a statement terminator

 

What is the difference between scalar types and structured types?

scalar types are:

types without component parts

structured types are:

types which have component pars - like records and arrays

 

FORTRAN uses implicit type declarations while Ada and Pascal do not.      

What do we mean by implicit typing?

in implicit typing, the type of the variable is determined either by its name (as in FORTRAN) or by what is assigned to it (as in Snobol)

Do you consider implicit typing a plus or a minus?  

plus

minus

Why?

plus - provides for greater flexibility

minus - makes language less reliable more subject to programmer error

 

 

 Some programming languages have key words, and some languages have reserved words. 

What is a key word?

a word that has pre-defined meaning when used in a particular context

 

Give an example of a key word in a language we've looked at this semester:

if, do,

What language did your key word come from?

FORTRAN

 

Programming Languages Exam

Scope Question

 

Name ____________                           Max Points:  10                         Points Earned:  _____

 

Here's a program written in pseudocode (although it may look like a real language).

 

 

program a;

const  x = 4;

var z: integer;

 

procedure p(x: integer);

var y : integer;

begin {p}

y := z * x;

print (y);

end procedure p;

 

 

procedure q (x : integer);

var z: integer;

 

procedure r:

var y : integer;

begin {r}

  y := z + 5;

  p(y);

end procedure r;

 

begin  {q}

  z := 2;

  r;

end procedure q;

 

begin {a}

  z := 8;

  q(x);

end program a;

 

 

 

p

r

q

a

 

 

2. What value will be printed if we assume that the program is using static scope rules? 56      

 

3. What value will be printed if we assume that the program is using  dynamic scope rules?   14

Programming Languages Exam

FOR LOOP

 

Name ____________               Max Points:  10                  Points Earned:  _____

 

 

Here is a pseudo-code for loop (which represents a syntactically correct Pascal,  Ada  or Java FOR loop or a FORTRAN DO loop.   Answer each of the questions which follow the loop with regard to any three of the following four languages:  FORTRAN, Pascal, Ada and Java.  Cross out the column for the language you are not choosing.

 

var  m, n : integer;

 

      for i := m to n do

         begin

           output i

           <3>

         end;

 

 

Question

FORTRAN

Pascal

Ada

Java

Does changing the value of n at point <3> have any effect on the number of times the loop is executed ?

no

no

no

yes

Is it possible to jump out of the loop at point <3>

yes

yes

yes

yes

Is it possible to print the value of i after the loop has completed normally?

yes

yes

no

depends where it is declared

Is it possible to have the value of i be decremented as it goes from m to n?

yes

yes

yes

yes

  

 

       


Programming Languages Exam

Grammar Question

 

Name ____________                          Max Points:  15                         Points Earned:  _____

 

Given the  language specification below

 

            <start>     ::=  <someCs>  <someDs>

            <someCs>  ::=  c  c

            <someCs>  ::=  c c <someCs>

            <someDs>  ::=  d

            <someDs>  ::=  d  d  <someDs>

                       

a.         Draw 5 different parse trees generating legal strings in this language

      <start>

      /      \

    <someCs>     <someDs>

  /  |     \              | 

c   c  <someCs>     d

             / \     

             c   c              

<start>

/      \

<someCs> <someDs>

  /   \          |

c     c          d

 

<start>

/      \

<someCs> <someDs>

  /   \         / |  \

c     c       d  d  <someDs>

                           |

                           d

 

      <start>

      /      \

    <someCs>     <someDs>

  /  |     \             / |  \

c   c  <someCs>   d  d  <someDs>

              / \                |

             c   c               d

 

      <start>

      /      \

    <someCs>     <someDs>

  /  |     \             / |  \

c   c  <someCs>   d  d  <someDs>

              / \                 /  |  \

             c   c               d  d  <someDs>

                                               |

                                               d

        

 

b.        Show each of the strings you generated 

 

  c c c c d               c c d                 c c d d d           c c c c d d d                 c c c c d d d d d

 

 

c.         Describe in concise English what the strings in this language consist of.  Be careful to be accurate and precise.

 

An even number of Cs followed by an odd number of Ds.  There must be at least 2 Cs and 1 D.From Dershem & Jipping – 2nd edition – problem 12

 

Programming Languages Exam

Comparative Languages

 

Name ____________               Max Points: 15                 Points Earned:  _____

 

 

Rewrite the FORTRAN code containing a computed GOTO statement shown below in Pascal without GOTO statements.  Only write what is necessary to replace this code.  Assume that  all declarations, etc. are in place.

 

if number = 1 then

       number := number * 2

 else

       if number = 2 then

          number := number - 1

       else

          if number = 3 then

             number := 16;

 number := number * number ;

        GOTO (10,20,30)  NUMBER

      

10      NUMBER = NUMBER * 2

GOTO 60

20      NUMBER = NUMBER – 2

GOTO 60

30      NUMBER = 16

60   NUMBER = NUMBER * NUMBER

 

 

 

 

What would be stored in the memory locations shown below after execution of the following FORTRAN input statement?  The input data is shown in the box below.

     

              READ (5, 20)  A,B, I, X

 20         FORMAT (F3.2, F2.1, I3, F2.2)

 

3254657384729385712

 

A

3.45

B

4.6

I

573

X

.84

 

Write the FORTRAN output  and FORMAT statements  that would output each of the stored values with a single space separating each from the other.

 

            WRITE (6, 21) A,B,I,X

 21        FORMAT (1X,   F4.2, 1X, F3.1, 1X, I3, 1X, F3.2)

 

Show the output produced by the output statement you wrote above.  (Each box represents an output column)

3

.

4

5

 

4

.

6

 

5

7

3

 

.

8

4

 

 

 

 

 

            Programming Languages Exam

Parameter Passing

 

Name ____________               Max Points:  16                Points Earned:  _____

 

Below is a pseudo-code subprogram.

 

subprogram swap  ( number1,   number2)

 

local variable x

 

x  <- number 1

number1 <- number2

number2 <- x

 

end subprogram swap

 

Each part of this question asks you what will be printed upon return from the subprogram assuming that the pseudo-code represents syntactically correct code in the language specified.  For each part,  you should assume that:

      value1 and value2 are variables holding  ordinary integers

      value1 is initially 7

      value2 is initially 12

      swap is called with  parameters value1, value2  in that order

 

In each case,  what will be printed  after the return from swap, if value1 is printed followed by value2?

 

a.          The language is FORTRAN

Value1

12

Value2

7

 

b.     The language is  Pascal  and  number1 is a value parameter and number2 is a var parameter

  Value1

7

Value2

7

 

c.      The language is  Ada  and both parameters are  in out parameters

Value1

12

Value2

7

 

d.      The language is Java

Value1

7

Value2

12

 

                                                                                                                         

Programming Languages Exam

Ada For Loop Question

 

Name ____________               Max Points:  10      Points Earned:  _____

 

with Ada.Integer_text_io;
with Ada.text_io;

procedure testLoopFor  is

i : integer := 13;

begin
  for i in  3..5 loop    
    ada.Integer_text_io.put (i,3);
    for i in reverse 4..6 loop
      ada.Integer_text_io.put (i,3);
    end loop;
    ada.Integer_text_io.put (i,3);    
  end  loop;
  ada.Integer_text_io.put (i,3);
end testLoopFor;_   


The questions below all refer to the Ada code above

 

a.     Will the above Ada program compile?  NO because of typo – underscore in red at end of code snippet

¼§Ïtestloopfora.adb:17:18: identifier cannot start with underline

b.    Show the output!

ÏÏ«Ï ----jGRASP exec: C:\GNAT\bin\testLoopForA
ÏϧÏ
ÏϧϠ 3  6  5  4  3  4  6  5  4  4  5  6  5  4  5 13
ÏϧÏ
ÏÏ©Ï ----jGRASP: operation complete.

c. How many numbers will be printed?   16

  1. How many times will the number 4 be printed?  5
    e .How many times will the number 3 be printed?  2