Question

i got a compile error which i do not understand. i have a h/cpp file combination that does not contain a class but just defines some utility functions. when i try to use a struct that is defined in another class i get the error:

C2027错误:使用未定义的B类:C

因此,被 stripped弄到问题,藏书认为情况如此。

namespace A {
    void foo(B::C::SStruct const & Var);
}

标准结构的定义属于另一卷,当然包括。

namespace B {
    class C {
        public:
        struct SStruct { };
    };
}

the strange thing is, i can use this struct in other classes fine, it just seems to be related to this one h-file which contains just utility functions. what am i missing here? thanks!

Answer 1

在纠正失踪的半殖民地之后,这汇编了:

namespace B {
    class C {
        public:
        struct SStruct { };
    };
}
namespace A {
    void foo(B::C::SStruct const & Var);
}

显然,如果两个名称空间的次序被改变,那不会奏效。也许你只是大错的头脑。如果这是错误,那么这种错误设计就不正确了,那么你就不应允许标题在你的法典中处理。

Answer 2

我假定你指的是“C类”,而不是“Class C”。

struct SStruct is private to category C ( private being theailprofile of category members).

因此,在C类及其朋友之外,这并不明显,其中包括A:foo(......)。

Answer 3

Class C { 
        struct SStruct { }; 
    }

=>

class C { 
public:
        struct SStruct { }; 
    };

Answer 4

在定义之后,你的阶级就失去了一个半殖民地。应当:

namespace B {
    class C {
        public:
        struct SStruct { };
    }; // <=== Here
}

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