忆尔往矣

DEVELOPING ABSTRACT MODELS for our data and for the ways in which our programs process those data is an essential ingredient in the process of solving problems with a computer. In this series, we consider abstract data types (ADTs), which allow us to build programs that use high-level abstractions. With abstract data types, we can separate the conceptual transformations that our programs perform on our data from any particular data-structure representation and algorithm implementation. 继续阅读“Abstract Data Types～Abstract Objects and Collections of Objects”

Arrays, linked lists, and strings all provide simple ways to structure data sequentially. They provide a first level of abstraction that we can use to group objects in ways amenable to processing the objects efficiently. Having settled on these abstractions, we can use them in a hierarchical fashion to build up more complex structures. We can contemplate arrays of arrays, arrays of lists, arrays of strings, and so forth. 继续阅读“Elementary Data Structures ~ Compound Data Structures”

We use the term string to refer to a variable-length array of characters, defined by a starting point and by a string-termination character marking the end. Strings are valuable as low-level data structures, for two basic reasons. 继续阅读“Elementary Data Structures ~ Strings”

Linked lists bring us into a world of computing that is markedly different from that of arrays and structures. With arrays and structures, we save an item in memory and later refer to it by name (or by index) in much the same manner as we might put a piece of information in a file drawer or an address book; with linked lists, the manner in which we save information makes it more difficult to access but easier to rearrange. Working with data that are organized in linked lists is called list processing. 继续阅读“Elementary Data Structures ~ Linked Lists II”