非法成员初始化 [英] Illegal Member initialization

问题描述

我使用这个简单的类而不使用任何继承。

  class A 
 {
 int a; 
 int b; 
 
 public：
 A（int x，int y）{a = x; b = y;} 
 A（）：A（0,0）{}; 
〜A（）{}; 
}; 
 
 int main（）
 {
 A a1，a2（5，7）; 
} 
  

我收到此错误。

错误C2614：'A'：非法成员初始化：'A'不是基础或成员

$ b b

有关SO的类似问题，但它们与继承有关。

p>如果有人在C ++ 11中更详细地阐述了转发构造函数和这个特性，最好。

解决方案

可以使用C ++ 11，可以从 A（int，int）初始化 A（）。这是不可能在C ++ 03，你必须写两个单独的构造函数。

如果你想让你的代码在C ++ 03中工作，你有两个选项：

• 创建一个函数 init（int，int）每个构造函数。这是一个很好的选择，如果你的构造函数做了很多工作。


• 在两个构造函数中重复的行为。

您也可以从子类构造函数中调用基本构造函数。例如，如果您有

  class A {
 A（int，int）; 
}; 
 class B：public A {
 B（int，int）; 
}; 
  

您可以写

  B :: B（int x，int y）：A（x，y）{} 
  

这是你的编译器所说的 A不是一个基础，它是期待这种情况。

所有这些都与C ++ 03兼容。

您还可以升级您的编译器以支持C ++ 11功能。我不推荐这个，如果你在Linux工作，并希望你的项目在Windows中编译，因为Windows编译器不实现所有的C ++功能，Linux编译器做（除非你支付一个好的编译器）。

I am using this pretty simple class without using any inheritance.

class A
{
  int a;
  int b;

public:
 A(int x, int y) { a = x; b = y;}
 A() :A(0,0){};
 ~A(){};
} ;

int main ()
{
  A a1, a2(5, 7) ;
}

I get this error.

error C2614: 'A' : illegal member initialization: 'A' is not a base or member

There are similar questions on SO but they relate to inheritance. Can someone explain the reason and what does standard say about that?

EDIT:

It would be better if someone elaborate more on the forwarding constructor and this feature in C++11.

解决方案

If you can use C++11, you could initialize A() from A(int, int). This is not possible in C++03, where you have to write two separate constructors.

If you want your code to work in C++03, you have two options:

• Create a function init(int, int) and call it from each of your constructors. This is a good choice if your constructor does a lot of work.
• Duplicate behaviour in both constructors. This is a good choice when all you are doing are member initializations.

You can also call a base constructor from a child class constructor. For instance, if you have

class A {
    A(int, int);
};
class B : public A {
    B(int, int);
};

You could write

B::B(int x, int y) : A(x,y) {}

This is what your compiler means when it says that A is not a base, it is expecting this situation.

All of these are compatible with C++03.

You could also upgrade your compiler to support C++11 features. I wouldn't recommend this if you are working in Linux and want your project to compile in Windows because Windows compilers don't implement all the C++ features that Linux compilers do (unless you pay for a good compiler).

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