Chapter 17. Specialized Library Facilities

Exercise 17.1

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

tuple<int, int, int> threeInt(10, 20, 30);

Exercise 17.2

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

tuple<std::string, std::vector<std::string>, std::pair<std::string, int> t;

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.

TextQuery Definition | TextQuery Implementation | TextQuery Test

Exercise 17.4

Write and test your own version of the findBook function.

findBook function by tuple way | findBook Test

Exercise 17.5

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

findBook function by pair way | findBook Test

Exercise 17.6

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

findBook function without tuple or pair | findBook Test

Exercise 17.7

Explain which version of findBook you prefer and why.

I prefer the tuple version, because this version is more flexible.

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?

Nothing happened, it's the same as passed Sales_data(s). Because std::accumulate's third parameter is the initial value of the sum. It's will be zero whether Sales_data() or Sales_data(s). Check the constructor of Sales_data and the operator+= member for more information.

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): 64 bits, lower-order 6 bits are 100000, remaining bits are 0. (b): 00000000000011110110100110110101 (c): depends on what user has been input.

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.

bitset initialization and turn on test

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?

QuizResponses Definition

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.

QuizResponses Definition

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.

Test QuizResponses class

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.

Try error code 1

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.

I before E except after C rule

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.

[^c]ei says we want any such letter that is followed by the letters 'ei', This pattern describes strings containing exactly three characters. The test words in ex17_15 will all fail.