Question

In the following code I am getting the error:

a value of type (double*)(const double& arg) const cannot be assigned to an entity of type pt2calculateA

Any suggestions on how to make it work?

class myClass {
    private:

    typedef double (*pt2calculateA)(double);

    pt2calculateA calculateA[2];

public:

    myClass () {
        calculateA[0] = &calculateA1; //->error
        calculateA[1] = &calculateA2; //->error
    }

    double calculateA1(const double& arg) const {
            ...
    }

    double calculateA2(const double& arg) const {
        ...
    }
}

Answer 1

myClass::calculateA1() is not a function; rather, it is a member function. So the types are naturally not compatible.

The type of &myClass::calculcateA1 is double (myClass::*)(const double &) const, which is a pointer-to-member-function (PTFM). Note that you can only use a PTMF together with a pointer to an object instance (i.e. a myClass*).

If you change your typedef, you could at least store the pointers correctly:

typedef double (myClass::*pt2calculateA)(const double &) const;

You’ll have to say &myClass::calculateA1, etc., to take the address.

In C++11, you can initialize the array in the initializer list:

myClass() : calculateA{&myClass::calculateA1, &myClass::calculateA2} { }