How to call a function pointer within a struct class member

Question

I have a struct within a class which contains a list of commands and the function mapped to each command. I'm trying to then call a invoke the function pointer within another function in that class, However, the compiler keeps returning a called object type 'void (Csac::*)(char *, unsigned int, void *)' is not a function or function pointer error.

Here is a sample code

class Atom
{
  public:

    struct cmds_t
    {
        char cmd[20];
        void (Atom::* func)(char * data, unsigned int length, void * _atom);
    };

    void call_ptr_func(int i, char * data, unsigned int length, void * _atom);

  private:
    cmds_t atom_cmds[16] = {NULL};  

}

void atom::call_ptr_func(int i, char * data, unsigned int length, void * _atom) 
{   
    (this->atom_cmds[i].func)(data, length, NULL); 
}

void Atom::initialise_cmds()
{
  atom_cmds[0] = {.cmd = "!^",  .func = &Atom::funcA};
  atom_cmds[1] = {.cmd = "!TA", .func = &Atom::funcB};
   ...........
  atom_cmds[15] = {.cmd = "!S", .func = NULL};
}

void  Atom::funcA(char *data, unsigned int bytes, void * _atom)
{
  /// Stuff happens
}

Unfortunately, I can only compile with c++14 and I'm unable to use std::invoke. What am I doing wrong here?

https://stackoverflow.com/questions/12189057/how-to-call-through-a-member-function-pointer — Some programmer dude, Oct 03 '22 at 13:42
You are missing one `*` - it should be `(this->*atom_cmds[i].func)(data, length, NULL); ` — UnholySheep, Oct 03 '22 at 13:42
The "dereference a pointer-to-member" operators are `.*` and `->*`. — molbdnilo, Oct 03 '22 at 13:44
What's the purpose of `cmds_t atom_cmds[16] = {NULL}; `? Do you want to zero-initialize the array? — Ted Lyngmo, Oct 03 '22 at 13:45
@UnholySheep, that's exactly what I was missing, thanks. Not quite sure how I missed that. — Jadzn, Oct 03 '22 at 13:49
Tip for next time: Copy the actual code you've got so that you don't make a lot of mistakes when manually typing it into the question. Make sure it's a [mre]. — Ted Lyngmo, Oct 03 '22 at 13:53

How to call a function pointer within a struct class member

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