Expression must have a constant value

Hi,

I would like to define an array as:

int N = 100;

double Xn[N];

However, an error occurs: expression must have a constant value.

If I change the expression as follows:

double Xn[100].

no error occurs.

I don't know the reason.

The upper expression could be compiled in Dev-C++, and is easy to be modified.

Thanks.

PP