Question

I have the following class:

class DXStartupEncoder {
public:
   void EncodeA(unsigned char*& message) const;
   void EncodeB(unsigned char*& message) const;
   void EncodeC(unsigned char*& message) const;
   void EncodeD(unsigned char*& message) const;
};

<type> dn_sequence[] = {&DXStartupEncoder::EncodeA, &DXStartupEncoder::EncodeB, &DXStartupEncoder::EncodeC, &DXStartupEncoder::EncodeD };

But what is the type of this array of function pointers?

Answer 1

Use a typedef if you are not sure.

typedef void (DXStartupEncoder::*Encoder)(unsigned char*&) const;
Encoder dn_sequence[] = { .... };

In C++11 you could use decltype to deduce the type from value, so you don’t even need to know how to write the type of a member function pointer (auto can’t work, because the right hand side is an initializer_list):

decltype(&DXStartupEncoder::EncodeA) dn_sequence[] = { ... };

If you need to avoid the typedef, by the way, you’ll write it as:

void (DXStartupEncoder::*dn_sequence[])(unsigned char*&) const = { ... };