c-resources/CPlusPlus20ForProgrammers-m.../examples/ch14/fig14_14.cpp

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// fig14_14.cpp
// Demonstrating algorithms gcd, lcm, iota, reduce and partial_sum.
#include <array>
#include <algorithm>
#include <functional>
#include <iostream>
#include <iterator>
#include <numeric>
int main() {
std::ostream_iterator<int> output{std::cout, " "};
// calculate the greatest common divisor of two integers
std::cout << "std::gcd(75, 20): " << std::gcd(75, 20)
<< "\nstd::gcd(17, 13): " << std::gcd(75, 13);
// calculate the least common multiple of two integers
std::cout << "\n\nstd::lcm(3, 5): " << std::lcm(3, 5)
<< "\nstd::lcm(12, 9): " << std::lcm(12, 9);
// fill an array with integers using the std::iota algorithm
std::array<int, 5> ints{};
std::iota(ints.begin(), ints.end(), 1);
std::cout << "\n\nints: ";
std::ranges::copy(ints, output);
// reduce elements of a container to a single value
std::cout << "\n\nsum of ints: "
<< std::reduce(ints.begin(), ints.end())
<< "\nproduct of ints: "
<< std::reduce(ints.begin(), ints.end(), 1, std::multiplies{});
// calculate the partial sums of ints' elements
std::cout << "\n\nints: ";
std::ranges::copy(ints, output);
std::cout << "\n\npartial_sum of ints using std::plus by default: ";
std::partial_sum(ints.begin(), ints.end(), output);
std::cout << "\npartial_sum of ints using std::multiplies: ";
std::partial_sum(ints.begin(), ints.end(), output, std::multiplies{});
std::cout << "\n";
}
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