#include <variant>
#include <cstdio>
#include <vector>

template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; }; // (1)
template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;  // (2)

using var_t = std::variant<int, const char*>;

int main() {
    std::vector<var_t> vars = {1, 2, "Hello, World!"};

    for (auto& v : vars) {
        std::visit(overloaded {  // (3)
            [](int i) { printf("%d\n", i); },
            [](const char* str) { puts(str); }
        }, v);
    }

    return 0;
}

struct PrintInt { //(1)
    void operator() (int i) {
        printf("%d\n", i);
    }
};

struct PrintCString { // (2)
    void operator () (const char* str) {
        puts(str);
    }
};

struct Print : PrintInt, PrintCString { // (3)
    using PrintInt::operator();
    using PrintCString::operator();
};

template <class... Ts> // (1)
struct Print : Ts... {
    using Ts::operator()...;
};

int main() {
    std::vector<var_t> vars = {1, 2, "Hello, World!"};

    for (auto& v : vars) {
        std::visit(Print<PrintCString, PrintInt>{}, v); // (2)
    }

    return 0;
}

int main() {
    std::vector<var_t> vars = {1, 2, "Hello, World!"};
    auto PrintInt = [](int i) { printf("%d\n", i); }; // (1)
    auto PrintCString = [](const char* str) { puts(str); };

    for (auto& v : vars) {
        std::visit(
            Print<decltype(PrintCString), decltype(PrintInt)>{PrintCString, PrintInt}, // (2)
            v);
    }

    return 0;
}

template <class... Ts> // (1)
auto MakePrint(Ts... ts) {
    return Print<Ts...>{ts...};
}

int main() {
    std::vector<var_t> vars = {1, 2, "Hello, World!"};

    for (auto& v : vars) {
        std::visit(
            MakePrint( // (2)
                [](const char* str) { puts(str); },
                [](int i) { printf("%d\n", i); }
                ),
            v);
    }

    return 0;
}

std::tuple t(4, 3, 2.5); // same as auto t = std::make_tuple(4, 3, 2.5);

#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
// NOTE: These are not yet standardized, but are required to simulate the
// implicit deduction guide that should be generated had libc++ declared the
// tuple-like constructors "correctly"
template <class _Alloc, class ..._Args>
tuple(allocator_arg_t, const _Alloc&, tuple<_Args...> const&) -> tuple<_Args...>;
template <class _Alloc, class ..._Args>
tuple(allocator_arg_t, const _Alloc&, tuple<_Args...>&&) -> tuple<_Args...>;
#endif

#include <variant>
#include <cstdio>
#include <vector>

using var_t = std::variant<int, const char*>;

template <class... Ts>
struct Print : Ts... {
    using Ts::operator()...;
};

template <class...Ts> Print(Ts...) -> Print<Ts...>; // (1)

int main() {
    std::vector<var_t> vars = {1, 2, "Hello, World!"};
    for (auto& v : vars) {
        std::visit(
            Print{ // (2)
                [](const char* str) { puts(str); },
                [](int i) { printf("%d\n", i); }
            },
            v);
    }
    return 0;
}

std::variant<double, bool, std::string> var;

struct {
    void operator()(int) { std::cout << "int!\n"; }
    void operator()(std::string const&) { std::cout << "string!\n"; }
} visitor;

std::visit(visitor, var);

template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;

std::variant<double, bool, std::string> var;
std::visit(overloaded {
            [](auto arg) { std::cout << arg << ' '; },
            [](double arg) { std::cout << std::fixed << arg << ' '; },
            [](const std::string& arg) { std::cout << std::quoted(arg) << ' '; },
        }, var);

struct overloadInt{ 
    void operator(int arg){
        std::cout<<arg<<' ';
    } 
};
struct overload : overloadInt{
    using overloadInt::operator();
};

#include <iomanip>
#include <iostream>
#include <string>
#include <type_traits>
#include <variant>
#include <vector>

template<typename T, typename VARIANT_T>
struct is_variant_member_type;

template<typename T, typename... Ts>
struct is_variant_member_type<T, std::variant<Ts...>> 
  : public std::disjunction<std::is_same<T, Ts>...> {};


template <typename V > typename std::enable_if<is_variant_member_type<std::string,V>::value&&
    is_variant_member_type<double,V>::value>&&
    is_variant_member_type<int,V>::value>::type
match (V v)
{
    if  (std::holds_alternative<int>(v))
    	std::cout << std::get<int>(v) << ' '; 
    if (std::holds_alternative<std::string>(v))
        std::cout << std::quoted(std::get<std::string>(v)) << ' ';
    if  (std::holds_alternative<double>(v))
        std::cout<<std::fixed << std::get<double>(v) << ' ';
}

// the variant to visit
using var_t = std::variant<int, double, std::string>;

int main() {
    std::vector<var_t> vec = {10, 15l, 1.5, "hello"};
    for(auto& v: vec) {
        match(v);
    }
}

#include <algorithm>
bool iequals(const string& a, const string& b)
{
    return std::equal(a.begin(), a.end(),
                      b.begin(), b.end(),
                      [](char a, char b) {
                          return tolower(a) == tolower(b);
                      });
}

        //! 'Equals' predicate ( case insensitive )
        /*!
            This predicate holds when the test container is equal to the
            input container i.e. all elements in both containers are same.
            Elements are compared case insensitively.

            \param Input An input sequence
            \param Test A test sequence
            \param Loc A locale used for case insensitive comparison
            \return The result of the test

            \note This is a two-way version of \c std::equal algorithm

            \note This function provides the strong exception-safety guarantee
        */
        template<typename Range1T, typename Range2T>
        inline bool iequals( 
            const Range1T& Input, 
            const Range2T& Test,
            const std::locale& Loc=std::locale())
        {
            return ::boost::algorithm::equals(Input, Test, is_iequal(Loc));
        }