Question

I dont know how to ask but i try my best;

Simply

int a = 19;
int& b=a;
cout<<b<<endl;    //Output : 19

but now output is different after cout with hex

int a = 19;
int& b=a;
cout<<hex<<&a<<endl;     //0031F788
cout<<b<<endl;        //Output : 13

So why last output is 13?

Answer 1

Because the stream base was set to hexadecimal, and never back to decimal.

cout<<hex<<&a<<dec<<endl; // back to dec immediately, as it's done usually.