以 `int typedef my_int;` 形式的 Typedef 声明 [英] Typedef declaration in the form `int typedef my_int;`

问题描述

要将 my_int 声明为 int 的类型别名，我们可以这样写:

To declare my_int as a type alias for int we can write:

typedef int my_int;   // (1)

奇怪的是，以下似乎也定义了一个 int 别名:

Curiously, the following also seems to define an int alias:

int typedef my_int;   // (2)

我以前从未见过这样的语法.为什么有效?

I have never seen such syntax before. Why does it work?

推荐答案

我阅读 C++ 参考是这样的:(1)和(2)是形式

My reasoning after reading C++ reference is this: (1) and (2) are declarations of the form

specifiers-and-qualifiers declarators-and-initializers;

specifiers-and-qualifiers 是 typedef int 或 int typedef.

说明符和限定符的顺序无关紧要，(1) 和 (2) 都是类型别名的有效声明.例如，要为 const int 定义别名，我们原则上可以使用以下 6 种组合中的任何一种:

The order of specifiers and qualifiers doesn't matter, and both (1) and (2) are valid declarations of a type alias. For example, to define an alias for const int we can, in principle, use any of these 6 combinations:

typedef int const my_cint;
typedef const int my_cint;
int typedef const my_cint;
const typedef int my_cint;
int const typedef my_cint;
const int typedef my_cint;

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