Overview of the data structure, the data structure acquaintance

I. Overview:

Early people regard the computer as numerical tools to understand, is the feeling of course is used to calculate the computer, so the computer to solve the problem, should start with a specific problem between abstracted an appropriate data model, devised a solution to this data model algorithm, and then write a program, get an actual software.
In reality, we are more than numerical calculation to solve the problem, but needs some more scientific and effective means (such as tables, trees and graphs and other data structures) help, in order to better deal with the problem.

Therefore, the data structure is the operation target programming problems a study in non-numerical calculation, and the correlation between them and the operation
discipline problems.

Visible, the data structure in programming which occupies an important position.

                   程序设计 = 鼓据结构+算法

Second, the basic concepts and terminology

1, Data: descriptive notation objective things, the computer can operate the object, a computer can be identified, and input to the set of symbols processed by a computer. It includes not only the numerical data type integer, real, etc., further comprising a non-numeric type character and audio, images and video.

2, data elements: is composed of data, there is a certain sense of the basic unit, usually as a whole in the computer processing. Also it called a record.

For example, in humans, it is what data elements it? Of course people.

3, data items: a data element can be composed from the number of data items.

For example, people such data elements that can have eyes, ears, nose, mouth, hands, feet, these data items can have name, age, sex, birth address, telephone number and other data items. Item is the smallest indivisible unit.

Data entry is the smallest unit of data. But the real discussion of issues, data is the data structure elements in establishing the focus of the data model.

4, the data object: is a collection of data elements of the same nature, is a subset of the data.

What is it the same nature, means that the data elements with the same number and type of data items, for example, people have the name, date of birth, gender, etc. the same data item.

Then the structure of the data structure of what is it?

Structure, simply means that relationship, such as the molecular structure, that is composed of arrangement between the atoms of the molecules. Strict point that the structure refers to the various components with each other and arranged in a way, in the real world, between different data elements are not independent, but there is a specific relationship, these relationships will be called structures.

What data structure is that? Official concept

数据结构:是相互之间存在-种或多种特定关系的数据元素的集合。

One or more specific relationship, specifically what kind of relationship, which is to discuss the issue.

5, the logical structure

Refers to a logical structure of the logical relationships among data elements, i.e., from a logic description data. Regardless of the data it stores, and is independent of the computer
Logical structure data is divided into linear and nonlinear structural configuration
1. Between a set of data elements in addition to the relationship between structure "belong to a set," and nothing other relationships. Similar set of mathematical
2. There is only one relationship between the data elements of the linear structure structure. For example, line up
3. Many relationship exists between the data elements of the tree structure. For example, family genealogy
4. Many relationship exists between the data elements of FIG structure or mesh structure structure. For example, the map

6, the physical structure

It refers to a data structure stored in the structure representation (known as an image) in the computer, also known as the physical structure. It includes representation and representation of the relationship between data elements. The data storage structure is to implement the logical structure of the computer language, which relies on computer language. Storing configuration data are: sequential storage, chain stores, and the hash index storage memory.
1. Sequentially storing: physical storage location adjacent. (Ps i.e., physical location of the location information in the computer.)
2. Links memory: the physical location of storage may not be adjacent to find adjacent elements by recording the physical location of adjacent elements.
3. Index Storage: similar to the directory
4. Hash memory: calculating the physical address directly by key element.

Sequential storage structure: is the address of the data elements stored in contiguous memory locations, the relationship between the physical and logical relationships whose data are consistent

Storage Structure: is any data elements stored in the storage unit, the group of memory cells which may be continuous or may be discontinuous.

Is a problem-oriented logical structure, the physical structure and is computer-oriented, the basic goal is to store data and logic in a computer's memory.

6, abstract data types

数据类型: 是指一组性质相同的值的集合及定义在此集合上的一些操作的总称。

数据类型是按照值的不同进行划分的。在高级语言中，每个变盘、常量和表达式都有各自的取值范围。类型就用来说明变量或表达式的取值范围和所能进行的操作。

抽象：是指抽取出事物具有的普遍性的本质。

它是抽出问题的特征而忽略非本质的细节，是对具体事物的一个概括。抽象是一种思考问题的方式，它隐藏了繁杂的细节，只保留实现目标所必需的信息。

抽象数据类型(Abstract Dataη肘， ADT ) : 是指一个数学模型及定义在该模型上的一组操作。抽象数据类型的定义仅取决于它的一组逻辑特性，而与其在计算机内部如何表示和实现无关。

抽象数据类型体现了程序设计中问题分解、抽象和信息隐藏的特性。抽象数据类型把实际生活中的问题分解为多个规模小且窑易处理的问题，然后建立一个计算机能处理的数据模型，并把每个功能模块的实现细节作为一个独立的单元，从而使具体实现过程隐藏起来。