Chapter 4 Control Structures I Selection

Chapter 4: Control Structures I (Selection) TRUE/FALSE 1. A control structure alters the normal sequential flow of execution in a program. ANS: T PTS: 1 REF: 184 2. The result of a logical expression cannot be assigned to an int variable, but it can be assigned to a bool variable. ANS: F PTS: 1 REF: 188 3. In C++, both ! and != are relational operators. ANS: F PTS: 1 REF: 186 4. In C++, !, &&, and || are called relational operators. ANS: F PTS: 1 REF: 190 5. The expression (x >= 0 && x <= 100) evaluates to false if either x < 0 or x >= 100. ANS: F PTS: 1 REF: 191 6. Suppose P and Q are logical expressions. The logical expression P && Q is true if both P and Q are true. ANS: T PTS: 1 REF: 191 7. In C++, && has a higher precedence than ||. ANS: T PTS: 1 REF: 192 8. The operators != and == have the same order of precedence. ANS: T PTS: 1 REF: 192 9. A compound statement functions as if it was a single statement. ANS: T PTS: 1 REF: 203 10. If the expression in an assert statement evaluates to true, the program terminates. ANS: F PTS: 1 REF: 232 MULTIPLE CHOICE 1. In a ____ control structure, the computer executes particular statements depending on some condition(s). a. looping c. selection b. repetition d. sequence ANS: C PTS: 1 2. What does <= mean? a. less than b. greater than ANS: C REF: 184 c. less than or equal to d. greater than or equal to PTS: 1 REF: 186 3. Which of the following is a relational operator? a. = c. ! d. && b. == ANS: B PTS: 1 REF: 186 4. Which of the following is the “not equal to” relational operator? a. ! c. != d. & b. | ANS: C PTS: 1 REF: 186 5. Suppose x is 5 and y is 7. Choose the value of the following expression: (x != 7) && (x <= y) a. false c. 0 b. true d. null ANS: B PTS: 1 REF: 190 6. Suppose that x is an int variable. Which of the following expressions always evaluates to true? a. (x > 0) || ( x <= 0) c. (x > 0) && ( x <= 0) d. (x > 0) && (x == 0) b. (x >= 0) || (x == 0) ANS: A PTS: 1 REF: 190 7. Which of the following operators has the highest precedence? a. ! c. % d. = b. * ANS: A PTS: 1 REF: 192 8. Which of the following operators has the lowest precedence? a. ! c. && d. = b. || ANS: D PTS: 1 REF: 192 9. Which of the following expressions correctly determines that x is greater than 10 and less than 20? a. 10 < x < 20 c. 10 < x && x < 20 d. 10 < x || x < 20 b. (10 < x < 20) ANS: C PTS: 1 REF: 190-191 10. The expression in an if statement is sometimes called a(n) ____. a. selection statement c. decision maker b. action statement d. action maker ANS: C PTS: 1 REF: 197 11. What is the output of the following C++ code? int x = 35; int y = 45; int z; if (x > y) z = x + y; else z = y – x; cout << x << " " << y << " " << z << endl; a. 35 45 80 b. 35 45 10 ANS: B c. 35 45 –10 d. 35 45 0 PTS: 1 REF: 200-201 12. When one control statement is located within another, it is said to be ____. a. blocked c. nested b. compound d. closed ANS: C PTS: 1 REF: 204 13. What is the output of the following code? if (6 > 8) { cout << " ** " << endl ; cout << "****" << endl; } else if (9 == 4) cout << "***" << endl; else cout << "*" << endl; a. * b. ** ANS: A c. *** d. **** PTS: 1 REF: 204-206 14. Which of the following will cause a logical error if you are attempting to compare x to 5? a. if (x == 5) c. if (x <= 5) d. if (x >= 5) b. if (x = 5) ANS: B PTS: 1 REF: 218 15. The appearance of = in place of == resembles a(n) ____. a. syntax error c. compilation error b. silent killer d. input failure ANS: B PTS: 1 REF: 218 16. Assume you have three int variables: x = 2, y = 6, and z. Choose the value of z in the following expression: z = (y / x > 0) ? x : y;. a. 2 c. 4 d. 6 b. 3 ANS: A PTS: 1 REF: 219 17. The conditional operator ?: takes ____ arguments. a. two c. four b. three d. five ANS: B PTS: 1 REF: 219 18. What is the value of x after the following statements execute? int x; x = (5 <= 3 && 'A' < 'F') ? 3 : 4 a. 2 b. 3 ANS: C c. 4 d. 5 PTS: 1 REF: 219 19. To develop a program, you can use an informal mixture of C++ and ordinary language, called ____. a. assert code c. cppcode b. pseudocode d. source code ANS: B PTS: 1 REF: 220 20. What is the output of the following code? char lastInitial = 'S'; switch (lastInitial) { case 'A': cout << "section break; case 'B': cout << "section break; case 'C': cout << "section break; case 'D': cout << "section break; default: cout << "section } a. section 2 b. section 3 1" <> num; switch (num) { case 3: alpha++; break; case 4: case 6: alpha = alpha + 3; case 8: alpha = alpha + 4; break; default: alpha = alpha + 5; } cout << alpha << endl; a. 13 b. 14 ANS: A c. 17 d. 22 PTS: 1 REF: 228 23. What is the output of the following C++ code? int x = 55; int y = 5; switch (x % 7) { case 0: case 1: y++; case 2: case 3: y = y + 2; case 4: break; case 5: case 6: y = y – 3; } cout << y << endl; a. 2 b. 5 ANS: A c. 8 d. 10 PTS: 1 REF: 228 24. For a program to use the assert function, it must include which of the following? a. #include c. #include d. #include NDEBUG b. #include ANS: B PTS: 1 REF: 232 25. You can disable assert statements by using which of the following? a. #include c. #clear NDEBUG d. #define NDEBUG b. #define ANS: D PTS: 1 REF: 233 COMPLETION 1. In C++, the logical operator AND is represented by ____________________. ANS: && PTS: 1 REF: 190 2. The value of the expression 7 + 8 <= 15 is ____________________. ANS: true True PTS: 1 REF: 186 3. The symbol > is a(n) ____________________ operator. ANS: relational PTS: 1 REF: 186 4. A ____________________ operator allows you to make comparisions in a program. ANS: relational PTS: 1 REF: 186 5. Putting ____________________ in front of a logical expression reverses the value of that logical expression. ANS: ! PTS: 1 REF: 190 6. The value of the expression 6 < 5 || 'g' > 'a' && 7 < 4 is ____________________. ANS: false False PTS: 1 REF: 192-193 7. Suppose found = true and num = 6. The value of the expression (!found) || (num > 6) is ____________________. ANS: false False PTS: 1 REF: 192-193 8. The ____________________ of relational and logical operators is said to be from left to right. ANS: associativity PTS: 1 REF: 193 9. Putting a semicolon after the parentheses following the expression in an if statement (that is, before the statement) is a(n) ____________________ error. ANS: semantic PTS: 1 REF: 199 10. Consider the following statements. int score; string grade; if (score >= 65) grade = "pass"; else grade = "fail"; If score is equal to 75, the value of grade is "____________________". ANS: pass PTS: 1 REF: 200-201 11. Every else must be paired with a(n) ____________________. ANS: if PTS: 1 REF: 204 12. The term ____________________ describes a process in which the computer evaluates a logical expression from left to right and stops as soon as the value of the expression is known. ANS: short-circuit evaluation short circuit evaluation PTS: 1 REF: 207 13. Once an input stream enters a(n) ____________________ state, all subsequent input statements associated with that input stream are ignored, and the computer continues to execute the program, which produces erroneous results. ANS: fail PTS: 1 REF: 214 14. A(n) ____________________ structure does not require the evaluation of a logical expression. ANS: switch PTS: 1 REF: 223 15. To output results correctly, the switch structure must include a(n) ____________________ statement after each cout statement, except the last cout statement. ANS: break PTS: 1 REF: 231 Chapter 5: Control Structures II (Repetition) TRUE/FALSE 1. The statement in the body of a while loop acts as a decision maker. ANS: F PTS: 1 REF: 261 2. The following while loop terminates when j > 20. j = 0; while (j < 20) j++; ANS: F PTS: 1 REF: 262 3. The number of iterations of a counter-controlled loop is known in advance. ANS: T PTS: 1 REF: 264 4. Assume all variables are properly declared. The output of the following C++ code is 2 3 4 5. n = 1; while (n < 5) { n++; cout << n << " "; } ANS: T PTS: 1 REF: 265 5. In a counter-controlled while loop, the loop control variable must be initialized before the loop. ANS: T PTS: 1 REF: 264-265 6. In the case of the sentinel-controlled while loop, the first item is read before the while loop is entered.