c++ - Multiple Declaration error ignored in classes, why? -

consider following code fragment:

int test;                //global variable class base {      int test;           //private member of base    public:      void getit()      {           cin>>test;      } };  class derived: public base {    public:      void check()      {           test++;        //neither access global test nor member of base      } }; 

in above code, observe variable test. first declared globally , again declared inside class in private scope.

my question first question how compiler allowing multiple declaration variable test , why not giving error?

also, when function check() tries access test, compiler gives error. know private members not inherited , not accessible outside class, exists global variable, must accessible.

second question which test present inside check() whether global 1 or 1 declared inside class base? also, how access global test?

how compiler allowing multiple declaration variable test , why not giving error?

this basic tenet of c++'s scope rules. conceptually, it's no different declaring local variable same name global variable.

the test in global namespace not conflict test member variable (though 1 "hide" other when used in unqualified way, because member take priority during lookup).

this how language designed, , it's thing.

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also, when function check() tries access test, compiler gives error.

the important thing consider precisely what error is. it's not telling no symbol test can found; it's telling it's found member variable, , have no access it.

that tells access specifiers not affect visibility, accessibility:
your member test still hides global test, though can't access it.

to specify global test, you'd need write ::test.