Summary of data structure and application (1)------Data structure

1.1 What is data

data (Date) is an object that describes an objective thing and can be recognized and processed by a computer, which can be numeric, character, sound, image, etc.
A data element (Date Element) is the basic unit of data and is an individual in a data set that is usually considered and processed as a whole in a computer program. Data elements have different titles in different data structures, such as borrowing points in a tree structure, called vertices in a graph structure, and records in database tables. It can consist of one or more data items.
The data item is the smallest unit of data and cannot be divided.
The data Object is a collection of data elements of the same nature and is a subset of the data. 1.2 What is a data structure

structure is the relationship. Data Structure are a collection of one or more specific relationships that exist before each other. The data structure includes the logical structure, the storage structure and the three aspects of the corresponding operation. logical structure of 1.2.1 data

The logical structure of the data (Logical Structure of data) refers to the logical relationship between them. It is independent of the computer and can be used as a data model abstracted from specific problems. The logical structure of data usually has the following four kinds: set structure, linear structure, tree structure, mesh structure (also called graphic structure).

We refer to the logical structure of a one-to-one relationship between data elements as a linear structure, and a logical structure describing a one-to-many or many-to-many relationship between data elements is called a nonlinear structure.
The general concept of data structure refers to the logical structure of the information, without causing confusion, we refer to the logical structure of the data as data structure. storage structure of 1.2.2 data

the storage structure (Storage Structure of data, also known as the physical structure of data) refers to the representation (image) of data elements and their relationships in computer memory.
The storage structure of the data is four ways:
1) Sequential storage: In this storage mode, all the storage node cameras are stored in the connected storage area, and the relationship between the data elements is represented by the location relation between the storage nodes. The storage representation obtained by this method is called the sequential storage structure .
2) Chained storage: In this storage, each storage node not only stores one data element, but also stores a pointer. This pointer points to a storage node that is logically related to this storage node, which is a pointer to a logical relationship between data elements. The storage representation obtained by this method is called a chained storage structure .
3) Index storage: This kind of storage is usually stored in the node information at the same time, and also attached to the index table. Each item in the index table is called an index entry, and the general form is: (keyword, address), which is the storage address of a storage node or a group of storage nodes. The storage representation obtained by this method is called the index storage structure .
4) Hash Storage: The basic idea of this storage method is to store the keyword as the input of the selected hash (hash) function, and the value of the function as the storage address of the storage node. The storage representation obtained by this method is called the hash storage structure (hash Storage Structure).

A logical structure can be imaged into different storage structures. operation of 1.2.3 data

the operation of data refers to the way in which a set of data defined on the logical structure of data is used, and its implementation is carried out on the storage structure. Common basic operations include:
1) Building Data structures
2) Retrieving data elements
3) Inserting data elements
4) Delete data elements
5) Updating Data elements
6) Seek long
7) Read operation
8) Sort Operations 1.3 What is a data type

The

data type is a collection of values and a continuum that defines a set of operations on this collection. The
abstract data type is the extension and development of a data type concept, which refers to a mathematical model and the set of operations defined on it. The
is similar to an abstract function in Java, an interface. It simply defines the name of the method, describes the function to be implemented, determines the parameters that the method needs to pass in, but does not have a specific implementation. It provides the basis and target for the realization of the bottom layer.