pass member function as argument int template function

Hi everyone

I am trying to pass a member function as an argument to another template member funtion.
But during build time i am getting an error -: error: no matching function for call to 'A::do_op(int&, int&, <unresolved overloaded function type>)'

My .h file is :

Code:

---

class A
{
public:
    A();
 
    int test_op(int x,int y);
 
private:
    int add(int x, int y);
    int sub(int x, int y);
 
    template<class F>
    int do_op(int x, int y, F &fun)
    {
        return fun(x,y);
    }
 
};

---

cpp file :

Code:

---

template<class F>
int do_op_global(int x, int y, F &fun)
{
    return fun(x,y);
}
int add_global(int x, int y)
{
    return (x+y);
}
 
 
A::A()
{}
 
int A::add(int x, int y)
{
    return (x+y);
}
 
int A::sub(int x, int y)
{
    return (x-y);
}
 
int A::test_op(int x, int y)
{
    int m = do_op_global(x,y,add_global); // Statement 1
    int n = do_op(x,y,sub);               // Statement 2
 
    return (m+n);
}

---

Only statement 2 is giving error.

Is there any restriction for template function inside class ?
Please help me how i will pass a member function as argument.

thanks.

Use std::mem_fun (http://www.cplusplus.com/reference/functional/mem_fun/) it wraps member function inside function object.