int main()
{
    int low, high;
    char again='y';
    high=low=0;
    int firstn;
    int newarrsize=0;

    cout<<"tThe Sieve of Eratosthenes Algorithm"<<endl<<endl;
    do{

   //code to get low and high from user

    int* thearr= arr(high);
    for(int ix=0; ix<low;++ix){
      thearr[ix]=-1;
    }
    firstn=firstprime(high,thearr);
    do{
      crossout(high,thearr,firstn);
      firstn=firstprime(high,thearr);
    }while(firstn<= sqrt(high));

    if(firstn>sqrt(high))
      findzeros(thearr,high);

    int* thenewarr= primearr(thearr,high,newarrsize);

    cout<<"The prime numbers from "<<low<<" to "<<high<<" are: "<<endl;

    for(int ix=0; ix<=high; ++ix){
    cout<<thearr[ix]<<"  ";
    }

    cout<<endl<<endl;
    cout<<endl<<endl;
    cout<<"Try again with new boundaries? (y/n):"<<endl;
    cin>>again;

    delete[] thearr;
    delete[] thenewarr;

    }while(again=='y');

   return 0;
}

int* arr(int size){
    int* thearray = new int[size]();
    thearray[0] = -1;
    thearray[1] = -1;
    return thearray;
}

int firstprime(int size, int arr[]){
  int* end = arr + size;
  int* begin = arr;
    while(begin<end){
        if(*begin==0)
            return *begin;
        begin++;
    }
    return -1;
}

void crossout(int size, int*arr, int factor){
    int* end = arr + size;
    int* begin = arr;
    begin[factor]=1;
    while(begin<end){
        if(*begin==factor)
          *begin=-1;
        factor+=factor;
    }
}

void findzeros(int arr[], int size){
    int* end = arr + size;
    int* begin = arr;
    while(begin<end){
        if(*begin==0)
            *begin=1;
        begin++;
    }
}

int* primearr(int arr[], int size, int& newarrsize){
    int count=0;
    int* end = arr + size;
    int* begin = arr;
      while(begin<end){
        if(*begin==1)
          ++newarrsize;
        begin++;
      }
      begin=arr;

    int *newarray= new int[newarrsize];
      while(begin<end){
        if(*begin==1){
          newarray[count]=*begin;
        }
        begin++;
      }
    return newarray;
}