直接初始化是否等同于直接列表初始化？

Question

我有以下例子：

struct S{
   int x, y;
}

S s1{1};    // direct-initialization or direct-list-initialization ?
S s2{1, 2}; // direct-initialization or direct-list-initialization ?
S s3(1);    // direct-initialization or direct-list-initialization ?
S s4(1, 2); // direct-initialization or direct-list-initialization ?
int i1{10}; // direct-initialization or direct-list-initialization ?
int i2(10); // direct-initialization or direct-list-initialization ?

我的问题

我只需要知道上面语句中初始化的类型是什么？
这里有标准报价吗？

我已经检查了direct-initialization vs direct-list-initialization (C++)的问题，但还没有严格的答案。

Answer 1

来自 direct initialization's documentation:

T object ( arg );

T object ( arg1, arg2, ... ); (1)

T object { arg }; (2) (since C++11)

T ( other )

T ( arg1, arg2, ... ) (3)

Direct initialization is performed in the following situations:

initialization with a nonempty parenthesized list of expressions or braced-init-lists (since C++11)

initialization of an object of non-class type with a single brace-enclosed initializer (note: for class types and other uses of braced-init-list, see list-initialization)

initialization of a prvalue temporary (until C++17)the result object of a prvalue (since C++17) by functional cast or with a parenthesized expression list

来自List initialization：

Direct-list-initialization

T object { arg1, arg2, ... }; (1)

T { arg1, arg2, ... } (2)

现在我们可以使用上面的内容来回答您的问题了。

S s1{1};    // direct-list-initialization from direct-list init point 1 above
S s2{1, 2}; // direct-list-initialization from direct-list init point 1 above
S s3(1);    // direct-initialization from direct init point 1 above
S s4(1, 2); // direct-initialization from direct init point 1 above
int i1{10}; // direct-initialization from direct init point 2 above
int i2(10); // direct-initialization from direct init point 1 above

直接初始化是否等同于直接列表初始化？

Is direct-initialization equivalent to direct-list-initialization?

c++

initialization

list-initialization

direct-initialization