在没有参数的构造函数上没有括号是语言标准吗？ [英] Is no parentheses on a constructor with no arguments a language standard?

问题描述

我使用g ++在Cygwin中编译了一个C ++程序，我有一个类的构造函数没有参数。我有行：

I was compiling a C++ program in Cygwin using g++ and I had a class whose constructor had no arguments. I had the lines:

MyClass myObj();
myObj.function1();

当试图编译它时，我收到以下消息：

And when trying to compile it, I got the message:

错误：请求'myObj'中的成员'function1'，它是非类类型'MyClass（）（）（）'

error: request for member 'function1' in 'myObj', which is of non-class type 'MyClass ()()'

小的研究，我发现修复是将第一行改为
MyClass myObj;

After a little research, I found that the fix was to change that first line to MyClass myObj;

我可以发誓我已经做了空的构造函数声明与括号C ++之前。这可能是我使用的编译器的一个限制，或者语言标准真的说不使用没有参数的构造函数的圆括号。

I could swear I've done empty constructor declarations with parentheses in C++ before. Is this probably a limitation of the compiler I'm using or does the language standard really say don't use parentheses for a constructor without arguments?

推荐答案

虽然 MyClass myObj（）; 可以被解析为一个具有空初始化器或函数声明的对象定义，语言标准指定歧义总是在偏好的函数声明。在其他上下文中允许空括号初始化器。在 new 表达式中或构造一个值初始化的临时。

Although MyClass myObj(); could be parsed as an object definition with an empty initializer or a function declaration the language standard specifies that the ambiguity is always resolved in favour of the function declaration. An empty parentheses initializer is allowed in other contexts e.g. in a new expression or constructing a value-initialized temporary.

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