prog.cpp:11:15: error: using declaration cannot refer to a constructor
using CBase::CBase;
~~~~~~~^
prog.cpp:16:11: error: no matching constructor for initialization of 'CDerived'
CDerived d("1", "2", "3");
^ ~~~~~~~~~~~~~
prog.cpp:8:7: note: candidate constructor (the implicit copy constructor) not viable: requires 1 argument, but 3 were provided
class CDerived : CBase
^
prog.cpp:8:7: note: candidate constructor (the implicit default constructor) not viable: requires 0 arguments, but 3 were provided
2 errors generated.