Calling Member function pointers from vector list

Question

I'm new to function pointers and I wrote a small program, where main class use Test class to populate a list with member function pointers. And from my main class I want to call ExeFuns() to call each member function, which I'm not sure how to do. Any help is greatly appreciated. Thanks.

Test.h

Class Test{
  public : 
   void CallFun1(); 
   void CallFun2();

   void AddFuns(); 
   void ExeFuns();      
};

Test.cpp

std::vector<void (Test::*) ()> callist; 


void Test::AddFuns(){
  callist.push_back(&Test::CallFun1); 
  callist.push_back(&Test::CallFun2); 
}


void Test::ExeFuns(){
  for (int i = 0 ; i<eventlist.size(); i++)
  {
   callist[i](); // error!
  }
}

void Test::CallFun1(){ cout<<"Fun 1"<<endl; }
void Test::CallFun2(){ cout<<"Fun 2"<<endl; }

Main.cpp

main()
{
Test obj; 
obj.AddFuns(); 
obj.ExeFuns(); 
}

If you have a C++11 compatible compiler (almost all are today), then you might want to look into [`std::function`](http://en.cppreference.com/w/cpp/utility/functional/function) and [`std::bind`](http://en.cppreference.com/w/cpp/utility/functional/bind). If you don't have C++11, then [Boost.Function](http://www.boost.org/doc/libs/1_54_0/doc/html/function.html) and [Boost.Bind](http://www.boost.org/doc/libs/1_54_0/libs/bind/bind.html) do the same. — Some programmer dude, Oct 04 '13 at 05:35

score 1 · Accepted Answer · answered Oct 04 '13 at 05:42

1

In short, you need .* or -> operators to invoke member methods. Also, there are several compilation errors and one out of bounds access in your code. Here is the correct approach,

void Test::ExeFuns(){
  for (int i = 0 ; i<callist.size(); i++) // also there is out of bounds access (usage of <=) in your code
  {
    (this->*callist[i])(); // or (*this.*callist[i])();
  }
}

answered Oct 04 '13 at 05:42

Arun

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Thanks for your comments. How would I get the same result if I use vector::pop_back()? – bMathew Oct 04 '13 at 05:57
1

pop_back doesn't return any value, hence you can't use it to invoke the method, but you can still use vector::back() as (this->*callist.back())(); – Arun Oct 04 '13 at 06:23

score 0 · Answer 2 · edited May 23 '17 at 12:01

0

Those are not pointers to standalone functions, they are pointers to member functions of a class. As chris said, you need an object to call them on.

Check this SO question.

edited May 23 '17 at 12:01

Community

1
1

answered Oct 04 '13 at 05:38

Torp

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Calling Member function pointers from vector list

2 Answers2