Given an array of ints, return the length of the array.

Remember that, for arrays, length is a field (a public final int instance variable, which although publicly accessible is also read-only) not a method. This is unlike String objects, where length requires the parentheses. (There's a reason: Strings contain arrays of char primitives as immutable private instance variables, and to reduce storage space they don't have an extra field just for length. Instead, they use a method to return the length field value of the underlying array.)