Question

I want to make a static vector in a class and I want to resize the vectors when they are created. I’m trying to do this in the constructor or in the main function. But I can’t get it to work. The problem is that I can’t call a function of the vector class on this way.
This is what I have now:

#include <vector>

using namespace std;

class test
{
public:
    static vector<int> testvec;
    test();
};

test::test() //Not static
{
    test::testvec.resize(0);    //Try 1
}

vector<int> test::testvec.resize(0); //Try 2

int main()
{
    test::testvec.resize(0); //Try 3
    test testclass;


    system("pause");
    return false;

}

I need to handle all the data on the vector in every object, that is why I want to make the vector static.

Can someone help me with this?
Thanks!

Edit: grammer. Every method that I have tried gives a compile error.

Answer 1

When you declare a static member attribute you also need to define it:

class test {
public:
   static std::vector<int> v; // declaration
};
std::vector<int> test::v; // definition, note: no `static` here

You can optionally use a size to the constructor, which would avoid the need to resize:

std::vector<int> test::v( 10 ); // definition, create it with size==10

But you can still call resize from main if you prefer:

int main() { 
   test::v.resize( 20 );
}