c-resources/CPlusPlus20ForProgrammers-m.../examples/ch13/fig13_06.cpp

73 lines
3.0 KiB
C++

// fig13_06.cpp
// Standard library multiset class template
#include <algorithm> // copy algorithm
#include <fmt/format.h> // C++20: This will be #include <format>
#include <iostream>
#include <iterator> // ostream_iterator
#include <ranges>
#include <set> // multiset class-template definition
#include <vector>
int main() {
std::multiset<int, std::less<int>> ints{}; // multiset of int values
std::cout << fmt::format("15s in ints: {}\n", ints.count(15));
std::cout << "\nInserting two 15s into ints\n";
ints.insert(15); // insert 15 in ints
ints.insert(15); // insert 15 in ints
std::cout << fmt::format("15s in ints: {}\n\n", ints.count(15));
// search for 15 and 20 in ints; find returns an iterator
for (int i : {15, 20}) {
if (auto result{ints.find(i)}; result != ints.end()) {
std::cout << fmt::format("Found {} in ints\n", i);
}
else {
std::cout << fmt::format("Did not find {} in ints\n", i);
}
}
// search for 15 and 20 in ints; contains returns a bool
for (int i : {15, 20}) {
if (ints.contains(i)) {
std::cout << fmt::format("Found {} in ints\n", i);
}
else {
std::cout << fmt::format("Did not find {} in ints\n", i);
}
}
// insert elements of vector values into ints
const std::vector values{7, 22, 9, 1, 18, 30, 100, 22, 85, 13};
ints.insert(values.cbegin(), values.cend());
std::cout << "\nAfter insert, ints contains:\n";
std::ranges::copy(ints, std::ostream_iterator<int>{std::cout, " "});
// determine lower and upper bound of 22 in ints
std::cout << fmt::format(
"\n\nlower_bound(22): {}\nupper_bound(22): {}\n\n",
*ints.lower_bound(22), *ints.upper_bound(22));
// use equal_range to determine lower and upper bound of 22 in ints
auto p{ints.equal_range(22)};
std::cout << fmt::format(
"lower_bound(22): {}\nupper_bound(22): {}\n",
*(p.first), *(p.second));
}
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