C++中std::tuple和std::pair的高级用法

#include <iostream>
#include <utility>

int main() {
    std::pair<int, std::string> myPair(10, "Hello");
    std::cout << "First: " << myPair.first << ", Second: " << myPair.second << std::endl;

    // 使用std::make_pair创建std::pair
    auto p = std::make_pair(3, "cherry");
    std::cout << "First: " << p.first << ", Second: " << p.second << std::endl;

    return 0;
}

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

int main() {
    // 创建并初始化std::tuple
    std::tuple<int, double, std::string> myTuple(1, 3.14, std::string("Hello"));

    // 访问std::tuple中的元素
    int a;
    double b;
    std::string c;
    std::tie(a, b, c) = myTuple;
    std::cout << "a: " << a << "\n";
    std::cout << "b: " << b << "\n";
    std::cout << "c: " << c << "\n";

    // 使用std::make_tuple创建std::tuple
    auto t = std::make_tuple(2, 4.56, "World");
    std::cout << "First: " << std::get<0>(t) << ", Second: " << std::get<1>(t) << ", Third: " << std::get<2>(t) << std::endl;

    return 0;
}

#include <iostream>
#include <tuple>
#include <string>
#include <tuple_cat.h> // 注意：在某些编译器中，可能需要显式包含这个头文件，但在标准库中通常不需要

int main() {
    std::tuple<int, double> tuple1(1, 2.3);
    std::tuple<char, std::string> tuple2('a', "Hello");

    // 使用 std::tuple_cat 合并 tuple1 和 tuple2
    auto mergedTuple = std::tuple_cat(tuple1, tuple2);

    // 访问合并后的 tuple 元素
    std::cout << std::get<0>(mergedTuple) << ", "    // int: 1
              << std::get<1>(mergedTuple) << ", "    // double: 2.3
              << std::get<2>(mergedTuple) << ", "    // char: 'a'
              << std::get<3>(mergedTuple) << std::endl; // std::string: "Hello"

    return 0;
}

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

int main() {
    std::tuple<int, double, std::string> myTuple(1, 2.3, "Hello");

    // 使用 std::tie 解包 tuple 元素
    int a;
    double b;
    std::string c;
    std::tie(a, b, c) = myTuple;

    std::cout << "a: " << a << "\n"; // 输出: a: 1
    std::cout << "b: " << b << "\n"; // 输出: b: 2.3
    std::cout << "c: " << c << "\n"; // 输出: c: Hello

    return 0;
}

#include <iostream>
#include <utility>

int main() {
    std::pair<int, std::string> myPair(1, "Hello");

    // 使用 std::tie 解包 pair 元素
    int x;
    std::string y;
    std::tie(x, y) = myPair;

    std::cout << "x: " << x << "\n"; // 输出: x: 1
    std::cout << "y: " << y << "\n"; // 输出: y: Hello

    return 0;
}

#include <iostream>
#include <tuple>
#include <string>
#include <utility> // for std::ignore

int main() {
    std::tuple<int, double, std::string> myTuple(1, 2.3, "Hello");

    // 使用 std::ignore 忽略第二个元素
    int a;
    std::ignore = std::get<1>(myTuple); // 或者直接不写这个变量也可以，但 std::ignore 更显式
    std::string c;
    std::tie(a, std::ignore, c) = myTuple;

    std::cout << "a: " << a << "\n"; // 输出: a: 1
    std::cout << "c: " << c << "\n"; // 输出: c: Hello

    return 0;
}