c++ - Is it safe to access Base protected member this way? -

i have 2 classes:

class base { protected:    int x; };  class der: public base {    void acc(base& b)    {       b.*(&der::x) = 5;    } }; 

is safe access base protected member way (&der::x) ? i'm worried point wrong variable.

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this way pass accessing protected member of base class object.

the above code:

for might find difficult understand below line

b.*(&der::x) = 5; 

it can written as:

b.*(&(der::x)) = 5; 

as scope resolution operator can omitted have 1 variable named x in base , derived class.

b.*(&x) = 5; 

which nothing taking address of x , again dereferencing it. can written as:

b.x = 5; 

which hope might aware of. code won't compile if use b.x instead of 'b.*(&der::x) = 5;' 'x' protected , used bypass compiler rule prevents writing b.x = 5;