So we could, in theory, rewrite our example with std::ref in order to create std::reference_wrappers: However, we shouldn’t use that, because there is a simpler solution: std::tie. As a result, if we pass lvalue references to std::make_tuple, as we did in the above example, std::make_tuple will store the corresponding decayed types. The Tuple elements can be accessed using properties with a name pattern Item, which does not make sense. To make the above code more readable, we can name the tuple return type values. 2. make_tuple() :- make_tuple() is used to assign tuple with values. Template parameters Types... A list of types used for the elements, in the same order as they are going to be ordered in the tuple. Tuples are handy C++ components that appeared in C++11, and are a very useful help when programming with variadic templates. tuple型は複数個の値の組を表す tuple<値1の型, 値2の型, 値3の型, (...)> 変数名; (必要な分だけ型を書く)で宣言する make_tuple (値1, 値2, 値3, (...)) This class holds references to the objects that are passed to its constructor. And std::decay removes the const and the reference attributes of a type. Note that there is an exception to the behaviour of std::make_tuple when it determines the types to store inside the tuple: if some of the decayed type is std::reference_wrapper, then the tuple will have a T& at the corresponding positions. Check out this refresher). Tuples are handy C++ components that appeared in C++11, and are a very useful help when programming with variadic templates. Okay. パラメータパックの値からなるtupleオブジェクトを返す。 1. Vui lòng xem cách sử dụng mẫu bên dưới. So in our example, std::make_tuple creates a tuple of type std::tuple. Not quite what we wanted. Tôi đã triển khai "c ++ có tên Tuple" bằng cách sử dụng bộ tiền xử lý boost. To make things even simpler, C++ offers not one but three helpers to build tuples and make our variadic template code more expressive: std::make_tuple, std::tie and std::forward_as_tuple. Consider the following example of a class X that contains a tuple: values_ is a tuple of references (which is a legal thing, and can be useful–they came in handy in the smart output iterators library for example). So let’s use… std::make_tuple then! It contains some logic to determine the types of the values inside of the tuple it makes. To make things even simpler, C++ offers not one but three helpers to build tuples and make our variadic template code more expressive: std::make_tuple, std::tie and std::forward_as_tuple. タプルまたはチュープル（英: tuple ）とは、複数の構成要素からなる組を総称する一般概念。 数学や計算機科学などでは通常、順序付けられた対象の並びを表すために用いられる。 個別的には、n 個でできた組を英語で「 n-tuple 」と書き、日本語に訳す場合は通常「n 組」としている。 Then values_, the data member of class X, initialises all of its references (remember, it is a tuple of references) with the values inside of the unnamed, temporary tuple returned by std::make_tuple. Here is the whole snippet if you’d like to play around with it. C#7.0 introduced a new and improved version of Tuple over generic tuple and named it as ValueTuple. std::forward_as_tuple determines the types of the elements of the tuple like std::forward does: if it receives an lvalue then it will have an lvalue reference, and if it receives an rvalue then it will have an rvalue reference (not sure about lvalues and rvalues in C++? The ValueTuple is stored on the heap, which is easy to retrieve. A tuple is an object capable to hold a collection of elements. tuple就是加强版的pair，可以含有多个元素。 tuple初始定义时，就必须确定每个元素的类型。 比如定义一个三个元素的tuple： tuple tp; 将输入的值放进tuple： make_tuple函数返回一个tuple。 int x,y,z; cin>>x>>y>>z; v Dereferencing those references therefore leads to undefined behaviour. I'm your host on Fluent C++. To illustrate, consider the following example: This program compiles (which implies that the static_assert has its condition verified). Into a tuple, tôi nhận được so … Hello, my name is Jonathan Boccara it... 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