Jump to content
  • Advertisement
Sign in to follow this  
denebo

C++ Function pointer help

This topic is 3002 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I'm trying to simulate (without the use of a GUI) a simple button that stores a function and executes it when pressed. The program compiles correctly, but then gives this error: Unhandled exception at 0xcccccccc in Testing.exe: 0xC0000005: Access violation. Here's the code:
#include <iostream>

using namespace std;

class Button
{
public:
	void (*function_) ();

	Button(void (*function) ())
	{

	}

	void click()
	{
		function_();
	}
};

void printLine()
{
	cout << "Button clicked!\n";
}

int main()
{
	Button b1(printLine);
	b1.click();

	return 0;
}

Share this post


Link to post
Share on other sites
Advertisement
Quote:

void (*function_) ();



Button(void (*function) ())

{



}


You never actually store the function pointer you pass to the constructor. Either add function_ = function; somewhere in the constructor or do like this:


...

Button(void (*function)()) : function_(function)
{

...


But anyway, you might want to consider making a button base class instead with an "onclick" (or similar) virtual function. C++ supports virtual functions so we don't have to fiddle too much with function pointers :)

Share this post


Link to post
Share on other sites
Prefer boost::function over writing your own function storing/invocation code. It will seamlessly handle free functions versus member functions, while working across multiple compilers and platforms.

Share this post


Link to post
Share on other sites
Quote:
Original post by rneckelmann
Quote:

void (*function_) ();



Button(void (*function) ())

{



}


You never actually store the function pointer you pass to the constructor. Either add function_ = function; somewhere in the constructor or do like this:


...

Button(void (*function)()) : function_(function)
{

...


But anyway, you might want to consider making a button base class instead with an "onclick" (or similar) virtual function. C++ supports virtual functions so we don't have to fiddle too much with function pointers :)


...oh, I didn't even notice I hadn't stored the function hahah.

Thanks for the replies!

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!