Syntax Error Declaring Array & error C2133: 'pi' : unknown size

I am writing this code to solve an array problem but i keep getting errors.

i want to declare that pi[0] = [1,0,0,0,0] but it keeps giving me an error. I am trying to declare that because i want to evaluate   pi[n] = (pi[n-1]) * 3 for a set of n numbers until  pi[n] - pi[n-1] <= 200
I used the for loop insde because i want n to increase and put it in the do while loop so i can tell it to stop.
PLease help..... what am i doing wrong?


#include <iostream.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <iomanip>
using namespace std;





int main()
{
      int n;
      double pi[0] =  [1,0,0,0,0];

       do
  {
      
       for (n=1; n>100; n++)
                   
       double pi[n];
             
        pi[n] = (pi[n-1]) * 3;
      cout<<pi[n];

  }


while pi[n] - pi[n-1] <= 200;
      
return 0;
}