Rather than using #define to define constants it's better to just make constants:

const size_t SIZE = 10;

This gives you type control and avoids macro expansion problems like the one you encountered.

Using #define is almost the same as using your a text editor's 'find-and-replace' function. There are some cases where it's useful, but usually it causes more problems than it solves.

const int N = 10;

struct S {
  int i[N];
};

'array' is a keyword in C++ IIRC, so it's a good habit to not use it as a variable name. Rather than using #define to define constants it's better to just make constants:

const size_t SIZE = 10;

This gives you type control and avoids macro expansion problems like the one you encountered.

Using #define is almost the same as using your a text editor's 'find-and-replace' function. There are some cases where it's useful, but usually it causes more problems than it solves.

const int N = 10;

struct S {
  int i[N];
};