An array represents an indexed
collection of elements of the same type (called the base type). Because
each element has a unique index, arrays, unlike sets, can meaningfully contain
the same value more than once. Arrays can be allocated statically or dynamically.
数组表示相同类型的元素的可索引集合,这里所说的“相同类型”即数组的基类型(base type)。数组中每个元素都有一个唯一的索引,因此,与集合不同,同一数组中可以含有多个相同的值。数组的分配方式有两种:静态和动态。