There are two ways to initialize an array variable - either provide the contents, in
which case they define the length, or you don't provide the contents (in which
case you must provide the length in [ ] brackets).
You can also specify both size an initialisation parameters. This is useful when you have a fixed length array and know the data - the compiler will complain if the number of initialisers and array size don't match. This can save weird bugs if the array is not initialised completely. Don't use this often, but it has caught errors for me and is worth knowing.