#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;
}
C++ Function pointer help
Author
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:
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 :)
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.
Author
Quote:Original post by rneckelmannQuote: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!
This topic is closed to new replies.
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