Advanced Pascal Programming Language Problems
© 1998 by Dr. Thomas W. MacFarland -- All Rights Reserved
Instructions: Review the following program and see if you can
predict the outcome by completing a "pencil
trace" of the code.
Program output is provided at the end of this
page.
Compiler: The program was prepared using Standard Pascal
on a UNIX-based host computer.
% cat PASCAL/advanced_pencil-18.p
{ Advanced Pascal Programming Language Exercises
Dr. Thomas W. MacFarland
advanced_pencil-18.p
}
{ The purpose of this program is to:
1. Demonstrate the use of case statements in Standard
Pascal.
2. Demonstrate multiple values for a case statement by
the use of the Boolean "or" operator.
}
program Demonstrate_Case_1;
var Letter_Grade: char;
begin
writeln('What letter grade do you hope to earn? ');
writeln;
writeln('Enter A for letter grade A');
writeln('Enter B for letter grade B');
writeln('Enter C for letter grade C');
writeln('Enter D for letter Grade D');
writeln('enter F for letter Grade F');
writeln;
write('Enter the letter grade you hope to earn: ');
{Note: For the purpose of this pencil-trace program, }
{assume that user enters a lower case "a" at this point.}
read(Letter_Grade);
writeln;
case Letter_Grade of
'A' , 'a' : writeln('Letter grade = A');
'B' , 'b' : writeln('Letter grade = B');
'C' , 'c' : writeln('Letter grade = C');
'D' , 'd' : writeln('Letter grade = D');
'F' , 'f' : writeln('Letter grade = F');
'+', '-', '*',
'=', '<', '>',
'/' : writeln ('Oops ... you selected a math or operator symbol.');
'!', '@', '#',
'$', '%', ',
'&', '_', '~',
'`', '\',
'|' : writeln ('Oops ... you selected a special character.');
',', ';', '(',
')', '{', '}',
'[', ']' : writeln ('Oops ... you selected a punctuation mark.');
'0', '1', '2', '3',
'4', '5', '6', '7',
'8', '9' : writeln ('Oops ... you selected a digit.');
'E', 'e', 'G', 'g', 'H', 'h', 'I', 'i', 'J', 'j',
'K', 'k', 'L', 'l', 'M', 'm', 'N', 'n', 'O', 'o',
'P', 'p', 'Q', 'q', 'R', 'r', 'S', 's', 'T', 't',
'U', 'u', 'V', 'v', 'W', 'w', 'X', 'x', 'Y', 'y',
'Z', 'z' : writeln ('Oops .. you selected an out-of-range character.');
end; (* case *)
end. {advanced_pencil-18.p}
% pc PASCAL/advanced_pencil-18.p
% a.out
What letter grade do you hope to earn?
Enter A for letter grade A
Enter B for letter grade B
Enter C for letter grade C
Enter D for letter Grade D
enter F for letter Grade F
Enter the letter grade you hope to earn: a
Letter grade = A
% a.out
What letter grade do you hope to earn?
Enter A for letter grade A
Enter B for letter grade B
Enter C for letter grade C
Enter D for letter Grade D
enter F for letter Grade F
Enter the letter grade you hope to earn: A
Letter grade = A
% a.out
What letter grade do you hope to earn?
Enter A for letter grade A
Enter B for letter grade B
Enter C for letter grade C
Enter D for letter Grade D
enter F for letter Grade F
Enter the letter grade you hope to earn: g
Oops .. you selected an out-of-range character.
% a.out
What letter grade do you hope to earn?
Enter A for letter grade A
Enter B for letter grade B
Enter C for letter grade C
Enter D for letter Grade D
enter F for letter Grade F
Enter the letter grade you hope to earn: G
Oops .. you selected an out-of-range character.
% a.out
What letter grade do you hope to earn?
Enter A for letter grade A
Enter B for letter grade B
Enter C for letter grade C
Enter D for letter Grade D
enter F for letter Grade F
Enter the letter grade you hope to earn: \
Oops ... you selected a special character.
% a.out
What letter grade do you hope to earn?
Enter A for letter grade A
Enter B for letter grade B
Enter C for letter grade C
Enter D for letter Grade D
enter F for letter Grade F
Enter the letter grade you hope to earn: ,
Oops ... you selected a punctuation mark.
% a.out
What letter grade do you hope to earn?
Enter A for letter grade A
Enter B for letter grade B
Enter C for letter grade C
Enter D for letter Grade D
enter F for letter Grade F
Enter the letter grade you hope to earn: 9
Oops ... you selected a digit.