The main point here is to show that `a[b]` and `b[a]` are the same thing where
one is a pointer and the other is an integer. It also shows random stuff you
can do with templates.

```cpp
#include <stdio.h>

template <typename T, int X=9>
void boing(const char* s) {
  T a[4];
  T* aa = &(a[X]);
  T* aaa = &(X[a]);
  printf("%20s: %lu (%d) -- %p %p\n",s,sizeof(T),X,aa,aaa);
}

int main() {
  boing<char>("char");
  boing<int>("int");
  boing<long,17>("long");
}
```
Output
```
                char: 1 (9) -- 0x7fff4592680d 0x7fff4592680d
                 int: 4 (9) -- 0x7fff45926814 0x7fff45926814
                long: 8 (17) -- 0x7fff45926868 0x7fff45926868
```