stl学习记录(2)

#include <iostream>
#include <utility>
#include <tuple>
#include <complex>
#include <string>

using namespace std;

// 代码 改编自 C++标准库——自学教程与参考手册  英文第二版

//====================================
// tuple io
template <int IDX,int MAX,typename... Args>
struct PRINT_TUPLE{
    static void print(ostream& strm, const tuple<Args...>& t){
        strm << get<IDX>(t) << (IDX + 1 == MAX ? "" : ",");
        PRINT_TUPLE<IDX + 1, MAX, Args...>::print(strm,t);
    }
};

template <int MAX,typename... Args>
struct PRINT_TUPLE<MAX, MAX, Args...>{
    static void print(ostream& strm, const tuple<Args...>& t){
    }
};

template <typename... Args>
ostream& operator << (ostream& strm,
    tuple<Args...>& t)
{
    strm << "[";
    PRINT_TUPLE<0, sizeof...(Args), Args...>::print(strm,t);
    return strm << "]";
}


//====================================


class Foo{
public:
    Foo(tuple<int, float>){
        cout << "Foo::Foo(tuple)" << endl;
    }

    template <typename... Args>
    Foo(Args... args){
        cout << "Foo::Foo(atgs...)" << endl;
    }
};

int _tmain(int argc, _TCHAR* argv[])
{
    // cpp11 后 一些新语法 在STL中得使用
    tuple<int, double>t(1,2.22);

    pair<int, Foo>p1(42, t);

    pair<int, Foo>p2(piecewise_construct, make_tuple(42), t);

    // 使用 ref() 表示对变量的引用
    int i = 0;
    auto p = make_pair(ref(i), ref(i)); // 创建 pair<int&,int&>
    ++p.first;
    ++p.second;
    cout << "i = " << i << endl;

    // tie() 演示
    pair<char, char> q = make_pair(‘c‘,‘b‘);
    char c;
    tie(ignore, c) = q; // char c == ‘b‘

    //
    tuple<string, int, int, complex<double>> tt;
    tuple<int, double,string> t1(41,6.3,"nico");

    cout << get<0>(t1) << " ";
    cout << get<1>(t1) << " ";
    cout << get<2>(t1) << " ";
    cout << endl;

    auto t2 = make_tuple(22,44,"nico");
    get<1>(t1) = get<1>(t2);
    t1 = t2;
    
    // tuple io
    tuple <int, double, string> iot(77, 1.1, "more light");
    cout << "io: " << iot << endl;

    return 0;
}