Initialize static array with values

Question

I have a class which is entirely static. Inside the class is a pointer to a list of integers of variable length. The functions inside the class depend on the first value in the list being initialized to 2 before they are called. Some of the functions are also called very frequently so I don't want to set that value first thing in every function.

Here is an example of the header:

class Foo{
public:
  static void f1();
private:
  static int* list;
}

and the .cpp file, globally (outside other function calls):

int* Foo::list = new int[10];

I need to initialize list[0] =2 somehow but that is not allowed in the same location as I have the list initializer.

"I need to initialize list[0] =2 somehow but that is not allowed in the same location as I have the list initializer." So? — Lightness Races in Orbit
– Lightness Races in Orbit, Commented Jun 8, 2015 at 19:17
@LightnessRacesinOrbit - Could be a base class with lots of constants. For example shape colours. — Ed Heal
– Ed Heal, Commented Jun 8, 2015 at 19:24
@AndyG: The initialiser can. Crucially, the initialiser is not "anybody but Foo". — Lightness Races in Orbit
– Lightness Races in Orbit, Commented Jun 8, 2015 at 19:48
I hope that static is not on your definition in real life, since it is invalid. — Lightness Races in Orbit
– Lightness Races in Orbit, Commented Jun 8, 2015 at 19:49

Vlad from Moscow · Accepted Answer · 2015-06-08 19:43:23Z

1

If your compiler supports C++ 2011 then write

int* Foo::list = new int[10] { 2 };

Another way is for example to define a private static function. For example

class Foo
{
// ...
private:
    static int *list;
    static int * init() 
    {
        int *p = new int[10];
        p[0] = 2;
        return p;
    }       
};

int* Foo::list = Foo::init();

edited Jun 8, 2015 at 19:43

answered Jun 8, 2015 at 19:20

Vlad from Moscow

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