错误：请求成员'..'在'..'是非类类型 [英] error: request for member '..' in '..' which is of non-class type

问题描述

我有一个类有两个构造函数，一个没有参数，一个接受一个参数。

I have a class with two constructors, one that takes no arguments and one that takes one argument.

使用接受一个参数的构造函数。但是，如果我使用没有参数的构造函数创建对象，我会收到一个错误。

Creating objects using the constructor that takes one argument works as expected. However, if I create objects using the constructor that takes no arguments, I get an error.

例如，如果我编译这个代码（使用g ++ 4.0.1）。 ..

For instance, if I compile this code (using g++ 4.0.1)...

class Foo
{
  public:
    Foo() {};
    Foo(int a) {};
    void bar() {};
};

int main()
{
  // this works...
  Foo foo1(1);
  foo1.bar();

  // this does not...
  Foo foo2();
  foo2.bar();

  return 0;
}

...我收到以下错误：

... I get the following error:

nonclass.cpp: In function ‘int main(int, const char**)’:
nonclass.cpp:17: error: request for member ‘bar’ in ‘foo2’, which is of non-class type ‘Foo ()()’

为什么是这样的，如何使它工作？

Why is this, and how do I make it work?

推荐答案

Foo foo2();

更改为

Foo foo2;

您得到错误，因为编译器认为

You get the error because compiler thinks of

Foo foo2()

'foo2'和返回类型'Foo'。

as of function declaration with name 'foo2' and the return type 'Foo'.

但在这种情况下如果我们改成 Foo foo2 编译器可能会显示错误重载的调用'Foo（）'是不明确的。

But in that case If we change to Foo foo2 , the compiler might show the error " call of overloaded ‘Foo()’ is ambiguous".

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