Thread: How to use pointer to a function

If you want to use a member function inside a class like that, you really need to pass the class. A member function call has an extra hidden parameter (this) that is not present in normal function calls, so the function you are passing is not compatible with your prototype function for test2().

--
Mats

Class members have a much more complex syntax... I don't remember exactly how it goes - pretty much lately, I've only used templates to do this. Someone else might help you on that front.
But your syntax is working for an ordinary non-class function pointer.

I think it should be:

Code:

#include <cstdio>

using namespace std;

class test {
public:
	int t(int);
};

int test::t(int a) {
	return a;
}

void test2(int (test::*f)(int), test& t) {
	printf("&#37;d", (t.*f)(2));
}

int main()
{
	test b;
	test2(&test::t, b);
}

However, I would also ask: why do you want to do this?

http://www.newty.de/fpt/index.html

Use typedefs in such case. They're very useful at hiding grotesque syntax. When I use function pointers, I've almost always used typedefs.

Well yes, I think I can agree there

If the function pointer is even moderately complicated, typedefs are a must. For example, a function in xuni has this prototype:

Code:

typedef void (*init_func_t)(void *vdata, struct smode_t *smode,
    struct font_t *font, struct theme_t *theme, struct gui_t *gui,
    struct resource_t *settings);
typedef void (*start_func_t)(void *vdata, struct theme_t *theme,
    struct gui_t *gui);
typedef int (*event_func_t)(enum panel_type_t *mode, SDL_Event *event,
    void *vdata, struct smode_t *smode, struct font_t *font,
    struct theme_t *theme, struct gui_t *gui);
typedef int (*set_widget_sel_func_t)(enum panel_type_t mode, int xp, int yp,
    int click, void *vdata, struct smode_t *smode, struct theme_t *theme,
    struct gui_t *gui);
typedef int (*perform_click_func_t)(int id, enum panel_type_t *mode,
    void *vdata, struct smode_t *smode, struct gui_t *gui);
typedef void (*paint_func_t)(void *vdata, enum panel_type_t mode,
    struct smode_t *smode, struct font_t *font, struct theme_t *theme,
    struct gui_t *gui);
typedef void (*free_func_t)(void *vdata, struct gui_t *gui);

void add_view(struct loop_data_t *data, void *vdata, int frameupdate,
    init_func_t init_func, start_func_t start_func, event_func_t event_func,
    set_widget_sel_func_t set_widget_sel_func,
    perform_click_func_t perform_click_func, paint_func_t paint_func,
    free_func_t free_func);

That's a really badly designed function and I'm hoping to get rid of it soon, but just imagine what that function would look like without those typedefs . . . .

And since no one's mentioned it yet that I can see: don't use void main(), use int main(). http://faq.cprogramming.com/cgi-bin/...&id=1043284376