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 'IFTHENELSE':
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 / OUTPUT12345
ABC
A B C
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 / OUTPUT3 9 2
-7 0 6
(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 / OUTPUT1
2
3
4
(b) Rewrite the statements in between CASEEND with the IFTHEN-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 / OUTPUT1
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 / Unit Price1 50 / $25.00
51 100 / $24.50
101 200 / $24.00
More than 200 / $23.00
Write a program on the program sheet provided to do ALL of the followings:
(a) Declare variables of suitable types:
Variable nameMeaning
num_batthe number of batteries to be ordered
unit_pricethe corresponding unit price
amountthe 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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