CLASSES - ISO C++ forbids in-class initialization of non-const static member 'pi'

[KickAz]

Hello I have a little problem I don't undestand what the problem is can someone explain to me?



error: ISO C++ forbids initialization of member `pi'
error: making `pi' static|
ISO C++ forbids in-class initialization of non-const static member 'pi'

#include <iostream>

using namespace std;

class circle
{
    public:
             double pi=3.14;
        double s(double r)
        {
            double S;
            S=2*r*pi;
            return S;
        }
        double p(double r)
        {
            double P;
            P=r*r*pi;
            return P;
        }
};

int main()
{
    double r;
    cout<<"Enter the radius"<<endl;
    cin>>r;
    circle k;
    k.p(r);
    k.s(r);
    return 0;
}

[TarikNeaj]

The reason you're getting the error I believe is because you are initializing a variable in your class. double pi=3.14;

As far as I know, you werent able to do that before c++11. But since c++11 you can do it no problem. I just tested your program and it runs fine for me. Are you like using a really old version of c++?

Maybe someone else can come and explain. Either way, how to get around this is to just create the variable pi, then initialize it in the constructor.

[Aaron Vienneau]

Prior to C++ 11, in order to initialize a variable in your class, you needed to declare it as const static - denoting that it is [1] immutable (const) and [2] shared between all instantiated objects of that class (static).

Post C++ 11, the compiler should take care of that detail for you. However, if you're using an older compiler, it may complain. Specifically, with g++, you have to include the -std=c++11 flag in the compile command, eg:

g++ -std=c++11 source.cpp -o source

If you're using an up-to-date compiler like VS, it should compile without complaint.