chap17

Answers To Non-programming Exercises

Contents

• Exercise 17.1
• Exercise 17.2
• Exercise 17.3
• Exercise 17.4
• Exercise 17.5
• Exercise 17.6
• Exercise 17.7
• Exercise 17.8
• Exercise 17.9
• Exercise 17.10
• Exercise 17.11
• Exercise 17.12
• Exercise 17.13
• Exercise 17.14
• Exercise 17.15
• Exercise 17.16
• Exercise 17.17
• Exercise 17.18
• Exercise 17.19
• Exercise 17.20
• Exercise 17.21
• Exercise 17.22
• Exercise 17.23
• Exercise 17.24
• Exercise 17.25
• Exercise 17.26
• Exercise 17.27
• Exercise 17.28
• Exercise 17.29
• Exercise 17.30
• Exercise 17.31
• Exercise 17.32
• Exercise 17.33
• Exercise 17.34
• Exercise 17.35
• Exercise 17.36
• Exercise 17.37
• Exercise 17.38
• Exercise 17.39

Exercise 17.1

Define a tuple that holds three int values and initialize the members to 10, 20, and 30.

Exer17_01_02.cpp

Exercise 17.2

Define a tuple that holds a string, a vector, and a pair<string, int>.

Exer17_01_02.cpp

Exercise 17.3

Rewrite the TextQuery programs from § 12.3 (p. 484) to use a tuple instead of the QueryResult class. Explain which design you think is better and why.

Exer17_03.cpp | Exer17_03_TextQuery.cpp | Exer17_03_TextQuery.h

Exercise 17.4

Write and test your own version of the findBook function.

Exer17_04.cpp

Exercise 17.5

Rewrite findBook to return a pair that holds an index and a pair of iterators.

Exer17_05.cpp

Exercise 17.6

Rewrite findBook so that it does not use tuple or pair.

Exer17_06.cpp

Exercise 17.7

Explain which version of findBook you prefer and why.

In this example tuple is okay. We don't need to define a new class or use nested pair. Everything is clear.

Exercise 17.8

What would happen if we passed Sales_data() as the third parameter to accumulate in the last code example in this section?

If we pass Sales_data(), the isbn of the result is an empty string. Thus the output result would not be correct.

Exercise 17.9

Explain the bit pattern each of the following bitset objects contains:

(a) bitset<64> bitvec(32);
(b) bitset<32> bv(1010101);
(c) string bstr; cin >> bstr; bitset<8>bv(bstr);

• (a) bitvec has 64 bits. The positions from 0 to 5 are set as 100000, the rest are

• (b) bv has 32 bits, the binary representation of 1010101 is 1111 0110 1001 1011 0101. So the bits of bv are 0000 0000 0000 1111 0110 1001 1011 0101.
• (c) bv has 8 bits and is initialized by bstr.If bstr is shorter than 8, the rest high-order part of bv is set to 0. If bstr contains any character except '0' or '1', the constructor throws invalid_argument exception.

Exer17_09.cpp

Exercise 17.10

Using the sequence 1, 2, 3, 5, 8, 13, 21, initialize a bitset that has a 1 bit in each position corresponding to a number in this sequence. Default initialize another bitset and write a small program to turn on each of the appropriate bits.

Exer17_10.cpp

Exercise 17.11

Define a data structure that contains an integral object to track responses to a true/false quiz containing 10 questions. What changes, if any, would you need to make in your data structure if the quiz had 100 questions?

Exer17_11_12_13.cpp | Exer17_11_quiz.h

Exercise 17.12

Using the data structure from the previous question, write a function that takes a question number and a value to indicate a true/false answer and updates the quiz results accordingly.

Exer17_11_12_13.cpp

Exercise 17.13

Write an integral object that contains the correct answers for the true/false quiz. Use it to generate grades on the quiz for the data structure from the previous two exercises.

Exer17_11_12_13.cpp

Exercise 17.14

Write several regular expressions designed to trigger various errors. Run your program to see what output your compiler generates for each error.

Exer17_14.cpp

Exercise 17.15

Write a program using the pattern that finds words that violate the “i before e except after c” rule. Have your program prompt the user to supply a word and indicate whether the word is okay or not. Test your program with words that do and do not violate the rule.

Exer17_15.cpp

Exercise 17.16

What would happen if your regex object in the previous program were initialized with "[^c]ei"? Test your program using that pattern to see whether your expectations were correct.

If we use "[^c]ei" to initialize regex, only words made up of 3 characters would be checked.

Exer17_16.cpp

Exercise 17.17

Update your program so that it finds all the words in an input sequence that violiate the “ei” grammar rule.

Exer17_17.cpp

Exercise 17.18

Revise your program to ignore words that contain “ei” but are not misspellings, such as “albeit” and “neighbor.”

Exer17_18.cpp

Exercise 17.19

Why is it okay to call m[4].str() without first checking whether m[4] was matched?

Because || uses short circuit evaluation. If m[4].str() is evaluated, that means m[4].str() == 0 is false, which means m[4].matched is true. Thus we can use m[4].str() directly.

Exercise 17.20

Write your own version of the program to validate phone numbers.

Exer17_20.cpp

Exercise 17.21

Rewrite your phone number program from § 8.3.2 (p. 323) to use the valid function defined in this section.

Exer17_21.cpp

Exercise 17.22

Rewrite your phone program so that it allows any number of whitespace characters to separate the three parts of a phone number.

Exer17_22.cpp

Exercise 17.23

Write a regular expression to find zip codes. A zip code can have five or nine digits. The first five digits can be separated from the remaining four by a dash.

Exer17_23.cpp

Exercise 17.24

Write your own version of the program to reformat phone numbers.

Exer17_24.cpp

Exercise 17.25

Rewrite your phone program so that it writes only the first phone number for each person.

Exer17_25.cpp

Exercise 17.26

Rewrite your phone program so that it writes only the second and subsequent phone numbers for people with more than one phone number.

Exer17_26.cpp

Exercise 17.27

Write a program that reformats a nine-digit zip code as ddddd-dddd.

Exer17_27.cpp

Exercise 17.28

Write a function that generates and returns a uniformly distributed random unsigned int each time it is called.

Exer17_28.cpp

Exercise 17.29

Allow the user to supply a seed as an optional argument to the function you wrote in the previous exercise.

Exer17_29.cpp

Exercise 17.30

Revise your function again this time to take a minimum and maximum value for the numbers that the function should return.

Exer17_30.cpp

Exercise 17.31

What would happen if we defined b and e inside the do loop of the game-playing program from this section?

If we defined b and e inside the do loop, every iteration would generate the same number.

Exercise 17.32

What would happen if we defined resp inside the loop?

If we defined resp inside the loop, we couldn't use resp in a condition of while, where it is out of scope.

Exercise 17.33

Write a version of the word transformation program from § 11.3.6 (p. 440) that allows multiple transformations for a given word and randomly selects which transformation to apply.

Exer17_33.cpp

Exercise 17.34

Write a program that illustrates the use of each manipulator in Tables 17.17 (p. 757) and 17.18.

Exer17_34.cpp

Exercise 17.35

Write a version of the program from page 758, that printed the square root of 2 but this time print hexadecimal digits in uppercase.

Exer17_35.cpp

Exercise 17.36

Modify the program from the previous exercise to print the various floating-point values so that they line up in a column.

Exer17_36.cpp

Exercise 17.37

Use the unformatted version of getline to read a file a line at a time. Test your program by giving it a file that contains empty lines as well as lines that are longer than the character array that you pass to getline.

Exer17_37.cpp

Exercise 17.38

Extend your program from the previous exercise to print each word you read onto its own line.

Exer17_38.cpp

Exercise 17.39

Write your own version of the seek program presented in this section.

Exer17_39.cpp