C ++:声明一个全局类并从其他类访问它? [英] C++: Declare a global class and access it from other classes?

问题描述

我有一个应该从main()全局声明并从程序中其他声明的类访问的类，该怎么做?

I have a class which should be declared globally from main() and accessed from other declared classes in the program, how do I do that?

class A{ 
    int i; 
    int value(){ return i;}
};

class B{ 
   global A a; //or extern?? 
   int calc(){
       return a.value()+10;
   }
}

main(){
   global A a;
   B b;
   cout<<b.calc();
}

推荐答案

您可能真的不想这样做，但是，如果必须-在包含main的文件中:

You probably really do not want to do this, but if you must - in the file that contains main:

#include "A.h"
A a;

int main() {
 ...
}

，然后在需要访问全局文件的文件中:

and then in the files that need to access the global:

#include "A.h" 
extern A a;

您需要将A的声明放入A.h头文件中，以使其正常工作.

You will need to put the declaration of A in the A.h header file in order for this to work.

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