Chapter 5 Quiz: Making Decisions — IF, CASE, and Boolean Logic

Chapter 5 Quiz: Making Decisions — IF, CASE, and Boolean Logic

Instructions: Choose the single best answer for each question. Answers are provided at the end.

Question 1. What is the output of this code when x is 7?

if x > 10 then
  WriteLn('A');
WriteLn('B');

(a) A
(b) B
(c) A followed by B
(d) No output

Question 2. Which of the following correctly uses if..then..else?

(a) if x > 5 then WriteLn('big'); else WriteLn('small');
(b) if x > 5 then WriteLn('big') else WriteLn('small');
(c) if x > 5 WriteLn('big') else WriteLn('small');
(d) if x > 5 then: WriteLn('big') else: WriteLn('small');

Question 3. In the expression if x > 5 and y < 10 then, Pascal evaluates this as:

(a) if (x > 5) and (y < 10) then — the intended meaning
(b) if x > (5 and y) < 10 then — a syntax error
(c) if (x > (5 and y)) < 10 then — likely a type mismatch error
(d) The code compiles and runs correctly without parentheses

Question 4. What does the {$B-} compiler directive do?

(a) Enables bounds checking
(b) Enables complete Boolean evaluation
(c) Enables short-circuit Boolean evaluation
(d) Disables Boolean type checking

Question 5. Given a := True, b := False, what is the value of a or b?

(a) True
(b) False
(c) Undefined
(d) Compiler error

Question 6. Which of the following types can be used as a case selector?

(a) Real
(b) String
(c) Char
(d) Double

Question 7. What happens if no case label matches the selector and there is no else clause?

(a) The program crashes with a runtime error
(b) The case statement is skipped entirely
(c) The first label's statement executes by default
(d) The compiler refuses to compile the program

Question 8. According to De Morgan's Laws, not (A or B) is equivalent to:

(a) (not A) or (not B)
(b) (not A) and (not B)
(c) not A or B
(d) A and B

Question 9. In this code, which if does the else belong to?

if a > 0 then
  if b > 0 then
    WriteLn('Both')
  else
    WriteLn('?');

(a) The outer if (a > 0)
(b) The inner if (b > 0)
(c) It is ambiguous and causes a compiler error
(d) It depends on the indentation

Question 10. What is the purpose of a guard clause?

(a) To protect variables from being modified
(b) To validate input early and exit if invalid, keeping the main logic flat
(c) To guard against compiler warnings
(d) To prevent the case statement from falling through

Question 11. Which case label syntax is valid in Pascal?

(a) case x of 'hello': WriteLn('hi'); end;
(b) case x of 1..5: WriteLn('range'); end;
(c) case x of 1.5: WriteLn('float'); end;
(d) case x of x > 5: WriteLn('big'); end;

Question 12. What is the output when score is 85?

case score of
  90..100: WriteLn('A');
  80..89:  WriteLn('B');
  70..79:  WriteLn('C');
else
  WriteLn('Below C');
end;

(a) A
(b) B
(c) C
(d) Below C

Question 13. With short-circuit evaluation enabled ({$B-}), what happens when x = 0 in this code?

if (x <> 0) and (100 div x > 5) then
  WriteLn('Yes');

(a) Division by zero error
(b) Prints "Yes"
(c) The second condition is not evaluated; nothing is printed
(d) Compiler error

Question 14. How many WriteLn calls execute when n is 25?

if n > 10 then
begin
  WriteLn('A');
  WriteLn('B');
end;
WriteLn('C');

(a) 1 (only C)
(b) 2 (A and C)
(c) 3 (A, B, and C)
(d) 2 (A and B)

Question 15. What is the correct way to check if a character is a lowercase vowel?

(a) if ch = 'a' or 'e' or 'i' or 'o' or 'u' then
(b) if ch in ['a', 'e', 'i', 'o', 'u'] then
(c) if (ch = 'a') or (ch = 'e') or (ch = 'i') or (ch = 'o') or (ch = 'u') then
(d) Both (b) and (c) are correct

Question 16. Why does Pascal's case statement require ordinal types?

(a) Because Niklaus Wirth preferred ordinal types
(b) Because the compiler can build a jump table for O(1) dispatch
(c) Because non-ordinal types cannot be compared
(d) Because it is a limitation that has never been fixed

Question 17. What is wrong with this code?

if balance = 0.0 then
  WriteLn('Zero balance');

(a) Nothing — it is correct
(b) balance should use := instead of =
(c) Comparing Real values with = is unreliable due to floating-point precision
(d) WriteLn cannot be inside an if statement

Question 18. In Pascal, what prevents the C-style bug of writing if (x = 5) when you mean if (x == 5)?

(a) Pascal does not have an = operator
(b) Pascal uses = for comparison and := for assignment, and := cannot appear in a Boolean expression
(c) Pascal requires the then keyword, which prevents the error
(d) There is no such protection in Pascal

Question 19. What is branch coverage?

(a) Testing that every variable is assigned at least once
(b) Testing that every line of code executes at least once
(c) Testing with inputs that exercise every branch of every conditional
(d) Testing that every procedure is called at least once

Question 20. Given the following code, which statement is true?

case grade of
  'A': WriteLn('Excellent');
  'B': WriteLn('Good');
  'C': WriteLn('Average');
  'D': WriteLn('Below average');
  'F': WriteLn('Failing');
end;

(a) If grade is 'E', the program crashes
(b) If grade is 'E', nothing happens — the case is skipped
(c) The code will not compile because there is no else clause
(d) If grade is 'a', it matches the 'A' label (case-insensitive)

Answer Key

(b) — x is 7, so x > 10 is False. The WriteLn('A') is skipped. WriteLn('B') is not part of the if and always executes.
(b) — No semicolon before else. Option (a) has a semicolon that terminates the if, making else orphaned.
(c) — and has higher precedence than > and <, so 5 and y is evaluated first as a bitwise operation. This produces a type mismatch or unexpected result. Always parenthesize: (x > 5) and (y < 10).
(c) — {$B-}` enables short-circuit evaluation. `{$B+} enables complete evaluation.
(a) — True or False evaluates to True.
(c) — Char is an ordinal type. Real, String, and Double are not ordinal.
(b) — In Free Pascal, if no label matches and there is no else, the entire case statement is skipped. No error occurs, but the behavior may not be what you intended. (Note: the ISO Pascal standard leaves this behavior undefined, and some implementations raise an error.)
(b) — De Morgan's Law: not (A or B) = (not A) and (not B).
(b) — else always matches the nearest unmatched if, which is the inner one (b > 0).
(b) — A guard clause validates early, exits if invalid, and keeps the main logic at a shallow nesting level.
(b) — Range labels like 1..5 are valid. String literals (a) cannot be case labels. Float values (c) are not ordinal. Expressions (d) are not valid labels.
(b) — 85 falls in the range 80..89, so "B" prints.
(c) — x <> 0 is False, so short-circuit evaluation skips the second operand. No division occurs, and nothing is printed.
(c) — n > 10 is True, so the begin..end block executes (A and B). Then C always executes. Total: 3.
(d) — Both the in set operator (b) and the chained or comparisons (c) are correct Pascal. Option (a) is syntactically invalid.
(b) — Ordinal types have a finite, countable set of values that map to integers, enabling the compiler to build a jump table for O(1) dispatch.
(c) — Floating-point comparison with = is unreliable due to rounding errors. Use Abs(balance) < epsilon instead.
(b) — Pascal uses := for assignment and = for comparison. Since := is a statement (not an expression), it cannot appear where a Boolean value is expected. This eliminates the entire class of accidental-assignment bugs.
(c) — Branch coverage ensures that every branch of every conditional (both true and false paths) is exercised by at least one test input.
(b) — In Free Pascal without an else clause, an unmatched value simply skips the case. Also, case on Char is case-sensitive, so 'a' does not match 'A'.