Топик: Organizing information
1. Introduction
2. The database
a) How is a database constructed?
3. Data structures
a) Pointers
b) Strings
c) Arrays
d) Static and Dynamic Data Structures
e) Stacks
4. Lists
5. Trees
1. Introduction
Information worked by the computer can organized in a variety of ways. Two important ways are that of a database and a spreadsheet.
On a database, work is arranged in fields and we will discuss these presently.
A spreadsheet will allow the user to keep accounts, make calculations and change information as necessary.
2. The database
A database is a sort of store where information is kept in an organized way. Access is gained through a keyboard or a special keypad which is a small hand-held unit containing keys which are pressed to work the set. The information can be of many different kinds. It is not always possible to gain access to a database and sometimes private pass-words are required in order that only certain people gain access. Some databases can be accessed through a specially adapted TV set using a modem. A modem is a small box that is specially made to change data into digital signals which can be sent through the telephone network.A database that can be accessed in this way is the Prestel system, consisting of thousands of pages of information and sometimes offered by libraries. Information given on Prestel is of a general nature, concerning such topics as entertainment, books for sale, airline journeys and so on. Information on a company database may, however, be of a very different kind. Such information might include names and addresses of employees, their salaries and general state of health. It might include goods manufactures by the company and suggested price lists. Much of the information a company might keep will probably be quite harmless, but other, more personal information about the company itself might be of a highly confidential nature requiring close security.
a) How is a database constructed?
A database can be organized in a variety of different ways depending upon the type of data that is to be stored. Take for instance a large collection of names and addresses, along with telephone numbers. This information will need to be broken down into fields, that is, in this case, the first name, surname, address and so on. Each category is known as a field. The field is either string (letters), or numeric (numbers). The database program usually asks you for your choice. These fields will be organized as:
Fields 1: surname (string)
Fields 2: fist name (string)
Fields 3: age (numeric)
Once the database has been set up, the computer will ask for the categories and they will be filled in as records. By using special commands the computer as able to search for names, addresses, telephone numbers or other fields and change, replace, add to, or even delete them altogether. Keeping information by this method saves much time and energy. Banks and building societies keep a lot of information about customers in this way.
Record № 8
Surname: Jones
First name: Michael
Address1: 33 Torr road
Address2: Liverpool
Telephone: 221-668973
Age: 41
3. Data structures
1. Most of the information we encounter in everyday life is structured in some way the commonest example is the words of our language, which are linked together in phrases, sentences and other more complex structures. The rules for constructing these structures are extremely complicated, yet we apply them by intuition.
2. Other examples of structured information include dictionaries, telephone directories and encyclopedias. These are all stores of information which would be useless if the information were not strictly arranged according to ma few simple rules. The structure of a collection of information makes it easy to locate individual items of information, and to insert new items, or delete items. The same reasoning applies to structured information stored in computers.
a) Pointers
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