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ch17.ixx
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ch17.ixx
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export module ch17;
import std;
export namespace ch17 {
namespace exercises {
namespace ex1 {
using namespace std;
using namespace ranges;
void printRange(string_view message, auto& range)
{
cout << message;
for (const auto& value : range) { cout << value << " "; }
cout << endl;
}
void test() {
auto result{ views::iota(10,101)
| views::transform([](const auto& value) { return static_cast<int>(pow(value, 2)); })
| views::filter([](const auto& value) { return value % 5 != 0; })
| views::transform([](const auto& value) { return to_string(value); }) };
printRange("Result: ", result);
}
void test_textbook() {
auto result{ views::iota(10, 100)
| views::transform([](const auto& v) { return v * v; })
| views::filter([](const auto& v) { return v % 5 != 0; })
| views::transform([](const auto& v) { return to_string(v); })
};
cout << "book answer:\n";
for (const auto& v : result) {
cout << v << " ";
}
cout << endl;
}
}
namespace ex2 {
using namespace std;
class Person
{
public:
Person(string first, string last)
: m_firstName{ move(first) }, m_lastName{ move(last) } { }
const string& getFirstName() const { return m_firstName; }
const string& getLastName() const { return m_lastName; }
private:
string m_firstName;
string m_lastName;
};
template <typename InputIter>
auto sum(InputIter begin, InputIter end)
{
auto sum{ *begin };
for (auto iter{ ++begin }; iter != end; ++iter) { sum += *iter; }
return sum;
}
void printRange(string_view message, auto& range)
{
cout << message;
for (const auto& value : range) { cout << value << " "; }
cout << endl;
}
void test() {
using Age = int;
vector<pair<Person, Age>> persons{
pair{ Person {"John", "White"} ,32 },
pair{ Person {"Chris", "Blue"} ,46 },
pair{ Person {"Zijian", "Guan"} ,23 },
pair{ Person {"df", "dv"} ,12 },
pair{ Person {"ff", "sdvv"} ,11 },
pair{ Person {"ff", "sdv"} ,65 },
pair{ Person {"vbb", "vbb"} ,89 }
};
auto result{ persons
| ranges::views::values
| ranges::views::filter([](const auto& value) { return value >= 12 && value <= 65; })
};
printRange("filtered ages", result);
cout << sum(begin(result), end(result))/ ranges::distance(result);
}
void test_textbook() {
vector persons{
pair{ Person{ "Izzie", "Fellows" }, 11 },
pair{ Person{ "Eshaan", "Cooper" }, 15 },
pair{ Person{ "Rick", "Crouch" }, 48 },
pair{ Person{ "Faye", "Pittman" }, 35 },
pair{ Person{ "Jude", "Bone" }, 69 },
pair{ Person{ "Ella-Louise", "Byers" }, 60 },
pair{ Person{ "Jad", "Lott" }, 75 },
pair{ Person{ "Teddie", "Love" }, 24 },
pair{ Person{ "Niko", "Silva" }, 16 },
pair{ Person{ "Bryan", "Melendez" }, 42 },
};
auto filteredAges{ ranges::views::common( // Convert the resulting range to a common range.
persons
| ranges::views::values // Only interested in the second element of each pair, the values.
| ranges::views::filter([](const auto& age) { return age >= 12 && age <= 65; })) }; // Filter on age.
auto count{ distance(begin(filteredAges), end(filteredAges)) }; // Cannot use ranges::size(filteredAges) here.
auto average{ sum(begin(filteredAges), end(filteredAges)) /
static_cast<double>(count) };
cout << "Average: " << average << endl;
}
void test_mix() {
vector persons{
pair{ Person{ "Izzie", "Fellows" }, 11 },
pair{ Person{ "Eshaan", "Cooper" }, 15 },
pair{ Person{ "Rick", "Crouch" }, 48 },
pair{ Person{ "Faye", "Pittman" }, 35 },
pair{ Person{ "Jude", "Bone" }, 69 },
pair{ Person{ "Ella-Louise", "Byers" }, 60 },
pair{ Person{ "Jad", "Lott" }, 75 },
pair{ Person{ "Teddie", "Love" }, 24 },
pair{ Person{ "Niko", "Silva" }, 16 },
pair{ Person{ "Bryan", "Melendez" }, 42 },
};
auto result{ persons
| ranges::views::values
| ranges::views::filter([](const auto& value) { return value >= 12 && value <= 65; })
};
printRange("filtered ages\n", result);
cout << "sum:";
cout << sum(begin(result), end(result)) / static_cast<double>(ranges::distance(result));
}
}
namespace ex3 {
using namespace std;
class Person
{
public:
Person(string first, string last)
: m_firstName{ move(first) }, m_lastName{ move(last) } { }
const string& getFirstName() const { return m_firstName; }
const string& getLastName() const { return m_lastName; }
private:
string m_firstName;
string m_lastName;
};
ostream& operator<<(ostream& ostr, const Person& person)
{
ostr << quoted(person.getFirstName()) << quoted(person.getLastName());
return ostr;
}
template <typename InputIter, typename OutputIter>
void myCopy(InputIter begin, InputIter end, OutputIter target)
{
for (auto iter{ begin }; iter != end; ++iter, ++target) { *target = *iter; }
}
void test() {
vector persons{
pair{ Person{ "Izzie", "Fellows" }, 11 },
pair{ Person{ "Eshaan", "Cooper" }, 15 },
pair{ Person{ "Rick", "Crouch" }, 48 },
pair{ Person{ "Faye", "Pittman" }, 35 },
pair{ Person{ "Jude", "Bone" }, 69 },
pair{ Person{ "Ella-Louise", "Byers" }, 60 },
pair{ Person{ "Jad", "Lott" }, 75 },
pair{ Person{ "Teddie", "Love" }, 24 },
pair{ Person{ "Niko", "Silva" }, 16 },
pair{ Person{ "Bryan", "Melendez" }, 42 },
};
auto result{ ranges::views::common( // Convert the resulting range to a common range.
persons
| ranges::views::keys // Only interested in the first element of each pair
| ranges::views::take(4))
};
myCopy(cbegin(result), cend(result), ostream_iterator<Person> { cout, "\n" });
auto lastNameResult{ ranges::views::common( // Convert the resulting range to a common range.
persons
| ranges::views::keys // Only interested in the first element of each pair
| ranges::views::take(4)
| ranges::views::transform([](const auto& person) { return person.getLastName(); })
)
};
myCopy(cbegin(lastNameResult), cend(lastNameResult), ostream_iterator<string> { cout, "\n" });
}
}
namespace ex4 {
using namespace std;
template <typename InputIter, typename OutputIter>
void myCopy(InputIter begin, InputIter end, OutputIter target)
{
for (auto iter{ begin }; iter != end; ++iter, ++target) { *target = *iter; }
}
void test() {
vector<int> results;
for (auto value : ranges::istream_view<int>(cin)
| ranges::views::take_while([](const auto& v) { return v != -1; })) {
results.push_back(value);
}
cout << "Terminating..." << endl;
myCopy(cbegin(results), cend(results), ostream_iterator<int> { cout, "\n" });
}
}
namespace ex_bonus {
using namespace std;
template <typename InputIter, typename OutputIter>
void myCopy(InputIter begin, InputIter end, OutputIter target)
{
for (auto iter{ begin }; iter != end; ++iter, ++target) { *target = *iter; }
}
void test() {
vector<int> results;
cout << "Enter numbers separated by whitespace." << endl;
cout << "Press Ctrl+Z followed by Enter to stop." << endl;
istream_iterator<int> numbersIter{ cin };
istream_iterator<int> endIter;
cout << "Terminating..." << endl;
myCopy(numbersIter, endIter, back_inserter(results));
myCopy(cbegin(results), cend(results), ostream_iterator<int> { cout, "\n" });
}
void test_textbook2() {
vector<int> results;
ranges::copy(ranges::istream_view<int>(cin)
| ranges::views::take_while([](const auto& v) { return v != -1; }),
back_inserter(results));
myCopy(cbegin(results), cend(results), ostream_iterator<int> { cout, "\n" });
}
}
}
}