c++ tuple demo

c++_tuple_demo.cpp

// 创建及获取元组内的对象  
std::tuple<double, std::string> tup1(3.14, "pi");  
auto tup2 = std::make_tuple("Hello World!", "abc", 3.14, 0);  
const char* data = std::get<1>(tup2);    // 得到abc  
double len = std::get<2>(tup2);        // 得到3.14  
  
// 拆箱：tie参数作为左值  
auto tup3 = std::make_tuple(3.14, 1, 'a');  
double a;  
int b;  
std::tie(a, b, std::ignore) = tup3;