POH CHAN KAI MEMORIAL COLLEGE
F. 4 Computer Studies
Class: ______(
) Name: ______________________________________
Date:______________
Practical 5: Conditional and Branching Statements
1. Jim writes a program to study the reserved words 'IF-THEN-ELSE':
PROGRAM P501;
VAR password : STRING;
BEGIN
WRITE('ENTER YOUR PASSWORD ... ');
READLN(password);
IF (password = ’ABC’) THEN
WRITELN('HI JIM, HOW DO YOU DO?')
ELSE
WRITELN('INCORRECT PASSWORD!')
END.
Run the program in your computer, try the following input and write down the output.
INPUT
12345
OUTPUT
ABC
ABC
2. The following program is to find the largest of any 3 given integers.
PROGRAM P502;
VAR a, b, c, max : INTEGER;
BEGIN
WRITE('INPUT A, B, C');
READLN(a, b, c);
max := a;
IF (b > max) THEN max := b;
IF (c > max) THEN max := c;
WRITELN('THE LARGEST ONE IS ',max)
END.
(a) The function of the line statement READLN(a, b, c) is to
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(b) The function of the first IF statement is
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(c) Run the program in your computer, try the following input and write down the computer output.
INPUT
3 9 2
-7 0 6
OUTPUT
(d) If the two IF statements are combined with an ELSE statement as follows:
IF ( b > max ) THEN max := b
ELSE
I F ( c > max ) THEN max := c;
Test the modified program with input of 1 2 3 .
Does the program perform the same function? (YES/NO)
__________
3. Study the following Pascal program.
PROGRAM P503;
VAR opt : 0..10;
BEGIN
WRITE('INPUT YOUR OPTION ... ');
READLN(opt);
CASE opt OF
1 : WRITELN('THIS IS OPTION ONE.');
2 : WRITELN('THIS IS OPTION TWO.');
3 : WRITELN('THIS IS OPTION THREE.')
END
END.
(a) Run the above program in your computer, write down the output if the input of opt is
INPUT
1
OUTPUT
2
3
4
(b) Rewrite the statements in between CASE-END with the IF-THEN-ELSE reserved words only.
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(c) Change the CASE block to the following by adding an ELSE line:
CASE opt OF
1 : WRITELN('THIS IS OPTION ONE.');
2 : WRITELN('THIS IS OPTION TWO.');
3 : WRITELN('THIS IS OPTION THREE.');
ELSE WRITELN('INVALID OPTION!')
END
Run the above program in your computer, write down the output if the input of opt is
INPUT
1
OUTPUT
3
4
7
4. ABC company sets the following rules for defining the unit price of a battery product during the
promotion period.
Number Of Batteries Ordered
1 - 50
51 - 100
101 - 200
More than 200
Unit Price
$25.00
$24.50
$24.00
$23.00
Write a program on the program sheet provided to do ALL of the followings:
(a) Declare variables of suitable types:
Variable name
num_bat
unit_price
amount
Meaning
the number of batteries to be ordered
the corresponding unit price
the total amount
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(b) Write the program segment to input the number of batteries to be ordered.
Program to calculate the amount charged with discount.
Please enter the number of batteries ordered: 120
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(c) By using IF-THEN-ELSE conditional structures, write a program segment to determine the unit price
of such an order, then output the unit price.
The unit price is $24.00 .
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(d) Write a PASCAL statement to calculate the total amount charged for the order.
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(e) Output the result.
The total amount is $2880.00 .
Thanks for your order, have a good day!
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