std::ranges::sort

#include <algorithm>
#include <array>
#include <functional>
#include <iomanip>
#include <iostream>
 
void print(auto const& seq) {
    for (auto const& elem : seq) {
        std::cout << elem << ' ';
    }   
    std::cout << '\n';
}
 
struct Particle {
    std::string name; double mass; // MeV
    template<class Os> friend
    Os& operator<< (Os& os, Particle const& p) {
        return os << "\n" << std::left
                  << std::setw(8) << p.name
                  << " : " << p.mass;
    }
};
 
int main()
{
    std::array s = {5, 7, 4, 2, 8, 6, 1, 9, 0, 3}; 
 
    namespace ranges = std::ranges;
 
    // 用默认 operator< 排序
    ranges::sort(s);
    print(s);
 
    // 用标准库比较函数对象排序
    ranges::sort(s, ranges::greater());
    print(s);
 
    // 用定制函数对象排序
    struct {
        bool operator()(int a, int b) const {   
            return a < b;
        }   
    } customLess;
    ranges::sort(s.begin(), s.end(), customLess);
    print(s);
 
    // 用 lambda 表达式排序
    ranges::sort(s, [](int a, int b) {
        return a > b;   
    });
    print(s);
 
    // 用投影排序
    Particle particles[] {
        {"Electron", 0.511}, {"Muon", 105.66}, {"Tau", 1776.86}, 
        {"Positron", 0.511}, {"Proton", 938.27}, {"Neutron", 939.57},
    };
    ranges::sort(particles, {}, &Particle::name); //< 按 name 排序
    print(particles);
    ranges::sort(particles, {}, &Particle::mass); //< 按 mass 排序
    print(particles);
}