CODEWITHSUNDEEP
cstructfunction-pointerspicxc8
Daniel
Daniel

Reputation: 107

Trying to call function using a void pointer inside a variable type

In the firmware that I am writing, I created a type of variable. Similar to what is below:

    struct SitemMenu {
      unsigned int id;
      char * text;
      void * submenu
    }
    typedef struct SitemMenu TitemMenu;

Be any function:

    void functionX () {
      ...
    }

If I create this variable:

    TitemMenu itemWhatever;

and do:

    itemWhatever.submenu = &function (X);

Can I call functionX doing:

    (*itemWhatever.submenu)();

I did something similar to this and the compiler give this answer:

    error: (183) function or function pointer required

Upvotes: 0

Views: 127

Answers (1)

brhans
brhans

Reputation: 402

Yes you can, but not quite the way you've written it.
A function pointer is not declared in quite the same way as a 'normal' pointer.
What you need is:

struct SitemMenu {
  unsigned int id;
  char * text;
  void (* submenu)(void); // this is a function pointer, as opposed to the 'normal' pointer above
};

typedef struct SitemMenu TitemMenu;
TitemMenu itemWhatever;

then, if you have some function declared with the same parameters and return type, like:
void functionX(void), then you can do:

itemWhatever.submenu = functionX;
itemWhatever.submenu();

Upvotes: 5

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