Name : Perfect Student Mark : 32 /25

1. Are the following variable names valid or invalid?

Valid or Invalid?

a. C3P0 Valid

b. 145R Invalid

c. R*2 Invalid

d. TimeAndDate Valid

(4 marks)

2. Point out the errors in the following program (by circling each error and attaching a brief explanation to each circle) :

program Age(input,output);

const Young = 14;

procedure GetAge(var TheAge:real); #Does not agree with type in calls
begin
write('Please enter your age :');
readln(TheAge);
end;

procedure Age(var TheAge:integer); #Procedure name same as program name
begin
if TheAge <= Young then
    writeln('A youngster');        #No ; before else
else writeln('A senior');
end;

var UserInput:integer;             #Should be before procedures

begin {----Main}
Age(17);                           #Passing constant to var parameter
GetAge(UserInput);
Age(UserInput);
end;                               #Should be a .

3. Convert the if-then-else statement in the following code into an equivalent case statement. You can assume that the user will enter an appropriate character.

var MomOrDad:char;
begin
readln(MomOrDad);
if (MomOrDad = 'M') or (MomOrDad = 'm') then
    writeln('Hi mom')
else if (MomOrDad = 'D') or (MomOrDad = 'd') then
        writeln('Hi dad');

case MomOrDad of
    'M','m':writeln('Hi mom');
    'D','d':writeln('Hi dad');
    end;

4. The formula to compute the number of different ways R items can be selected from a group of N items is N!/(R!*(N-R)!). This is called the number of combinations. Complete the function Combinations in the program below, to implement this formula.

program Gamble(input,output);
{----The core of a gambling program }
var Items,Select:integer;

function Factorial(N:integer):integer;
{----Computer the factorial of a number }
begin
if N <= 1 then
    Factorial:=1
else Factorial:=N*Factorial(N-1);
end;

function Combinations(Items,ToSelect:integer):integer;
begin
Combinations :=Factorial(Items) div
              (Factorial(ToSelect) * Factorial(Items - ToSelect));
end;

begin {----Main}
write('Enter number of items and number to select ');
readln(Items,Select);
writeln('There are ',Combinations(Items,Select),' ways to select ',
Select:1,' items from ',Items:1);
end.

5. The real variable Price holds the value 154.56 (to represent a value of $154.56). Give a Pascal statement that will write out Price in a suitable format.

writeln('$',Price:6:2)

6. What is the main

a) advantage Packed arrays are more space efficient

b) disadvantage Packed arrays are slower to access

of using a packed array (as opposed to a non-packed array)?
(2 marks)

7. Given the declarations

type DataType = record
        Size:real;
        Counted:integer;
        end;
    DataFileType = file of DataType;

write a procedure that reads a file of DataFileType, and writes all the Size and Counted fields' values to the screen, one pair per output line. The external name of the file is info.dat.

procedure ReadFile;
var	InputFile:DataFileType;
		  InputData:DataType;
begin
reset(InputFile,'info.dat');
while not(eof(InputFile)) do
    begin
    read(InputFile,InputData);
    writeln(InputData.Size,' ',InputData.Counted);
    end;
close(InputFile);
end;