Use member function as function pointer

Question

I've never used function pointers before and I'm having some trouble getting my code to work. This is what I have

TestClass.h:

class TestClass
{
    public:
        void function1();
        void function2();

        void function3(void (*funcPtr)(void))
        void function4();
};

TestClass.cpp

void TestClass::function1()
{
    //CODE
}

void TestClass::function2()
{
    //CODE
}

void TestClass::function3(void (*funcPtr)(void))
{
    //CODE
    funcPtr();
    //CODE
}

void TestClass::function4()
{
    function3(function1);
    function3(function2);
}

This give me the error

"nonstandard form for taking the address of a member function

I tried to add TestClass:: infront of the *funcPtr but that gives me even more errors

Non-static member functions aren't functions - you cannot call a member function. Instead, you have to invoke it on an object. — Kerrek SB
– Kerrek SB, Commented Oct 6, 2015 at 9:03
You want: void f(TestClass * obj, void (TestClass::* mf)()) { (obj->*mf)(); } and call it like f(this, &TestClass::function1). — Kerrek SB
– Kerrek SB, Commented Oct 6, 2015 at 9:04

Jarod42 · Accepted Answer · 2015-10-06 09:04:15Z

7

With member function pointer, it should be something like:

void TestClass::function3(void (TestClass::*funcPtr)())
{
    //CODE
    (this->*funcPtr)();
    //CODE
}

void TestClass::function4();
{
    function3(&TestClass::function1);
    function3(&TestClass::function2);
}

With function pointer

class TestClass
{
    public:
        static void function1(); // static added
        static void function2(); // static added

        void function3(void (*funcPtr)(void))
        void function4();
};

void TestClass::function3(void (*funcPtr)())
{
    //CODE
    funcPtr();
    //CODE
}

void TestClass::function4();
{
    function3(&TestClass::function1);
    function3(&TestClass::function2);
}

answered Oct 6, 2015 at 9:04

Jarod42

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Comments

user5405790 · Accepted Answer · 2015-10-06 13:46:55Z

1

I suggest you to use std::bind and std::function, which provide a better readability and more checking for you

http://en.cppreference.com/w/cpp/utility/functional/bind

#include <functional>

void TestClass::function3( std::function<void (void)> funcPtr )
{
    //CODE
    funcPtr();
    //CODE
}

void TestClass::function4()
{
    function3( std::bind(&TestClass::function1, this) );
    function3( std::bind(&TestClass::function2, this) );
}

answered Oct 6, 2015 at 13:46

user5405790

1 Comment

Jesper Evertsson Over a year ago

Currently working with embedded systems and don't have access to the newer versions of c++

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