【C++】 7_C++11 新特性-標準庫篇

tuple

文件:Test.cpp

#include <iostream>
#include <string>
#include <tuple>

using namespace std;

void test_1()
{
    cout << "test_1: ----------------------" << endl;

    // create and initialize a tuple explicitly
    tuple<int, float, string> t(41, 6.3, "nico");
    cout << "tuple<int, float, string>, sizeof = " << sizeof(t) << endl;

    // iterator over elements
    cout << "t: " << get<0>(t) << " " << get<1>(t) << " " << get<2>(t) << endl;
}

void test_2()
{
    cout << endl << "test_2: ----------------------" << endl;

    // create tuple with make_tuple()
    auto t = make_tuple(22, 44, "stacy");
    cout << "t: " << get<0>(t) << " " << get<1>(t) << " " << get<2>(t) << endl;
}

void test_3()
{
    cout << endl << "test_3: ----------------------" << endl;

    auto t1 = make_tuple(41, 6.3, "nico");
    auto t2 = make_tuple(22, 44, "stacy");

    // assign second value in t2 to t1
    get<1>(t1) = get<1>(t2);
    cout << "get<1>(t1) = " << get<1>(t1) << endl;
}

void test_4()
{
    cout << endl << "test_4: ----------------------" << endl;

    auto t1 = make_tuple(41, 6.3, "nico");
    auto t2 = make_tuple(22, 44, "stacy");

    // comparsion
    if (t1 < t2)
    {
        cout << "t1 < t2" << endl;
    }
    else
    {
        cout << "t2 < t1" << endl;
    }

    // assigns values for value
    t1 = t2;
    cout << "t1: " << get<0>(t1) << " " << get<1>(t1) << " " << get<2>(t1) << endl;
    cout << "t2: " << get<0>(t2) << " " << get<1>(t2) << " " << get<2>(t2) << endl;
}

void test_5()
{
    cout << endl << "test_5: ----------------------" << endl;

    tuple<int, float, string> t(77, 1.1, "more light");
    int il;
    float fl;
    string sl;

    // 批量賦值
    // std::tie會將變量的引用整合成一個tuple，從而實現批量賦值。
    tie(il, fl, sl) = t;

    cout << "il = " << il << ", fl = " << fl << ", sl = " << sl << endl;
}

void test_6()
{
    cout << endl << "test_6: ----------------------" << endl;

    typedef tuple<int, float, string> TupleType;
    cout << "tuple_size<TupleType>::value = " << tuple_size<TupleType>::value << endl;

    tuple_element<1, TupleType>::type fl = 1.1F;
    cout << "tuple_element<1, TupleType>::type fl : " << fl << endl;

    typedef tuple_element<1, TupleType>::type T;
    T fll = 1.1F;
    cout << "T fll : " << fll << endl;
}

ostream& operator<< (ostream &out, const tuple<int, float, string>& t)
{
    cout << get<0>(t) << " " << get<1>(t) << " " << get<2>(t) << endl;
}

void test_7()
{
    cout << endl << "test_7: ----------------------" << endl;

    auto t = make_tuple(41, 6.3, "nico");

    cout << t;
}

int main()
{
    test_1();
    test_2();
    test_3();
    test_4();
    test_5();
    test_6();
    test_7();

    return 0;
}

輸出：

test_1: ----------------------
tuple<int, float, string>, sizeof = 32
t: 41 6.3 nico

test_2: ----------------------
t: 22 44 stacy

test_3: ----------------------
get<1>(t1) = 44

test_4: ----------------------
t2 < t1
t1: 22 44 stacy
t2: 22 44 stacy

test_5: ----------------------
il = 77, fl = 1.1, sl = more light

test_6: ----------------------
tuple_size<TupleType>::value = 3
tuple_element<1, TupleType>::type fl : 1.1
T fll : 1.1

test_7: ----------------------
41 6.3 nico