C++ Using Object with pass function [closed] - c++

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I'm trying to build a object with other object and pass the function
Sorry for unclear description
the question is if the TESTobj is someone else object, and I build the new object(Gradebook) and use TESTobj to pass the function, pass the function without the object is no problem but in the object will error
error: no matching function for call to ‘TESTobj::SET(void (GradeBook::*)())’
no known conversion for argument 1 from ‘void (GradeBook::*)()’ to ‘void (*)()’
Here is Example:
void TESTobj::SET(void (*nu)())
{//point the function
this->nu=nu;
}
void TESTobj::Test()
{//implement the function
(*nu)();
}
void GradeBook::Grade()
{//the function I build
cout << "HELLO" <<endl;
}
void GradeBook::Set()
{
OBJ.SET(&GradeBook::Grade);//GotProblemHere
OBJ.Test();
}

Answer 1

GradeBook::Grade is a non-static member function, it needs to operate on an instance of GradeBook. You can't pass it in to a function expecting a plain function pointer.
You could change TESTobj::SET to accept std::function objects, then wrap your member function in a lambda:
void TESTobj::SET(std::function<void()> nu)
void GradeBook::Set()
{
OBJ.SET([this](){Grade();});
OBJ.Test();
}