c++ - Static object in struct -

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• what undefined reference/unresolved external symbol error , how fix it? 27 answers

i have class a method display(). create struct b static variable of type object a:

class a{ public :     void display()     {         cout << "in " << endl;     } }; typedef struct b{     static a; } bb;  //b::a.display(); int main() {     bb b;     bb::a.display();     return 0; } 

now error when try access a.

how can define static object in case?

you declared static a; did not define it. add following line before int main() , it'll link successfully:

a b::a;