The main concept of OOP and the element of the program is an object that combines both a set of data and actions on them. The object type in Turbo Rascal resembles a record type, but instead of the reserved word record, the word object is used, and in addition to the fields representing data, it also lists the headers of subroutines called methods. When specifying this type, after the reserved word object, all fields of the object and method headers are listed, after which the word end is written. So, in the example under consideration, the type (Connection) is used:
tConnection = object
PredElem: Pointer;
NextElem:Pointer;
In this type, PredElem and NextElem are pointers to the previous and subsequent elements in the structure (if there is no corresponding element, the pointer has the value nil). Pointers of the Pointer type are used, because elements can be different: they can be both line elements and strings. Next are the headers of two procedures and two functions that allow you to either set or get the values of object pointers.
Naturally, then all the methods used must be described in the same way as is done for subroutines in modules. In this case, it is allowed to write an abbreviated title of the method, but before it you should write the name of the object type to which this subroutine belongs, separated by a dot:
procedure tConnection.PutPredElem;
PredElem:=PredEl;
This is necessary because several different methods belonging to different objects can have the same name, as well as fields in different record types.
Some program objects, especially those at the beginning of the hierarchical tree, may not correspond to any real objects. So, for example, objects of the types tConnection (connection), tStructure (structure) and tOperation (operation) do not have any physical embodiment - they indicate only some dualities of other, real objects, such as strings and string elements. However, isolating these general properties into separate objects can be convenient, since it then allows them not to be repeated many times when describing real objects. Such objects are called abstract, and, as a rule, there are no variables of such types in a program.
12.2.1. Encapsulation
The term “encapsulation” refers to the combination of both parameters and actions on them in one object. In this case, the subroutines (methods) included in the object, as a rule, operate with data this object or access the methods of ancestor objects (see section 14.2.2). This allows you to combine all the properties of an object in one place, which makes it easier to understand the operation of the program, its debugging, and modification. So, for example, all properties of connections between elements in the structure of text are concentrated in the tConnection type. Typically, object data is not directly accessed from outside, although this is possible. Appropriate methods are usually used to access data. So, in the example under consideration, four methods are used for this purpose: PutPredElem, PutNextElem, GetPredElem and GetNextElem, with the help of which you can set and get the values of pointers to the previous and subsequent element. This circumstance is not far-fetched. This is what usually happens in our everyday life - we use certain parameters indirectly. If we take the already mentioned example of a computer, then it has such a parameter as the size of free memory on the hard drive. However, it is unlikely that the computer owner will directly count bytes to determine this parameter - special subroutines are used for this purpose.
Such indirect access to data allows us to avoid, in many cases, unexpected unwanted changes in parameters. In Turbo Rascal, for this purpose, a special reserved word private is used, which in principle prohibits direct access to certain data and methods of an object outside the module in which the object is described. In version 7.0 (a private section can be placed anywhere in the object (previously - only at the end (after the usual, available parameters and methods). So, if it is necessary to prohibit access to the data of an object of type tСonnection from the main program (remember that the main editor program is located in a separate file), this type can be described as follows:
tConnection = object
procedure РutPredElem(PredEl: Pointer);
procedure РutNextElem(NextEl: Рinter);
function GetPredElem: Рinter; I
function GetNextElem: Pointer;
private
PredElem: Pointer;
NextElem:Pointer;
If the private section is not at the end of the object, then to limit the range of the reserved word Rrivate you should place a reserved word after the private section public(accessible from outside) - only in version 7.0:
tConnection = object
PredElem: Pointer;
NextElem:Pointer;
procedure РutPredElem(PredEl: Pointer);
procedure РutNextElem(NextEl: Рinter);
function GetPredElem: Рinter; I
function GetNextElem: Pointer;
The main objects of Windows are files, folders and shortcuts.
File– a named collection of data on external media. In Windows OS they are also called documents. The file name consists of the actual name and extension. The name can be up to 255 characters long and can include numbers, space, and some special characters (! @ # $ % ^ & () ( ) _ -). The extension specifies the type of information contained in the file.
For example: doc txt frm wri - text
Bmp pcx tif pif wpg jpg - graphics pst pab – Email dbf db – databases xls – spreadsheet lib obj dll – libraries hlp – help files arj zip rar – archive files
In addition, in Windows, each file is associated with an icon corresponding to the file type, determined by the extension.
For example:
You can open the file double click according to his pictogram. Files are registered in folders (directories). Folder is a way of organizing and presenting system resources. A folder can contain other folders (subfolders), files, as well as objects such as a printer, disks, etc.
Folders are:
Window– a rectangular area of the screen designed to display objects, controls and information on the screen. In Windows OS there are four types of windows:
Dialog boxes are used when you need to configure or change something. Unlike folder windows, dialog boxes are not standardized, although they are standardized through the use of generic controls.
Majority dialog boxes contain more information than can fit on one window screen page. In this case, the dialog box creates tabs. Switching between tabs is done by clicking on its name.
Dialog boxes usually contain command buttons, which are used to execute commands.
For example:
- OK– closes the window and saves all settings made in it.
- Cancel- closing the window without saving the changes made.
- Review…- opens a dialog box with which you can conveniently search and select an object.
- Seal– Printing the current settings on the printer.
- Next>,<Назад - transition to the next stage of the wizard program or return to the previous stage.
Dialog boxes can also contain many other different controls,
For example:
- Text field– area for entering text information from the keyboard;
- Listbox, Combo Box, Dropdown List– allow you to select one parameter from a given set;
- Switches– allow you to select only one setting option out of several;
- Checkboxes– similar to switches, but unlike them, several checkboxes can be selected simultaneously;
- Counter– to enter numerical parameters;
- Positioning engine- clearly changes the adjustable parameters.
Examples of dialog boxes:
Topic 1. 2. Data type concept
The concept of a variable
Any program that processes data uses variables as operands in expressions. A variable is often defined as a “name” - “value” pair. The name corresponds to the address of the memory section allocated to the variable, and the value is the contents of this section.
Variable is a named area of computer memory allocated to store specific data, the value of which, in general, can change during program execution.
The description of variables in the program has the following format:
Let's look at each element of this description.
Name– identifier;
Every variable, constant, function, every expression in a program written in a high-level language has a specific type. Different types of data are stored and processed differently.
Data type defines:
Internal representation of data in computer memory;
Operations and functions that can be applied to objects of this type;
The set of values that values of this type can take.
All types of the C++ language are divided into basic And derivatives (compounds).
Basic Data Types
In programming languages, the main data types include data types for storing numbers (integer type, real type) and characters.
The C++ language defines seven basic data types: six for representing integer, real, character and logical values, and one special type void. The following keywords are defined to describe the six main ones:
int-whole,
char, wchar_t– symbolic,
float, double– real,
bool– logical.
In addition, there are four specifiers that specify the internal representation and range of values of standard types:
short - short ,
long - long ,
signed - signed (the most significant bit is interpreted as signed, 0 is positive, 1 is negative) ,
unsigned - unsigned .
Integer, character, and real types are also called arithmetic types.
Examples of variable descriptions:
int a,b;//two variables of integer type
float summa; // variable of real type
Let's look at the main types in more detail.
Under variable integer type (int) 2 or 4 bytes are allocated (for a 16-bit and 32-bit processor, respectively). short int – 2 bytes, long int – 4 bytes. Constants are assigned a type according to their type. By default, integer constants are interpreted as short and signed. To change this interpretation, you can use the suffixes – L,l,U,u. For example, 8L, 71u.
Character type(char) – 1 byte. (For wchar_t– implementation dependent, usually 2 bytes).
Let's look at the internal representation of a range of values using the char type as an example.
The smallest unsigned number, one byte long, is 00000000 2 =0
The largest unsigned number one byte long is 11111111 2 =255.
Therefore, the unsigned char type allows you to store 256 different characters with codes from 0 to 255.
The smallest positive number, one byte long, is 00000000 2 =0
The largest positive number one byte long is 01111111 2 =127
Largest negative number one byte long 11111111 2 =-1
The smallest negative number, one byte long, is 10000000 2 = -128
Recall that to obtain the absolute value of a negative number, it is inverted, that is, 0 is replaced by 1, 1 by 0, and one is added. For example, a negative number is 10000000. Invert - 01111111. Add 1
Therefore, the signed char type allows you to store 256 different characters with codes from -128 to 127.
Boolean type (bool)- 1 byte. The value of quantities of this type is either true ( true or 1), or false ( false or 0). Any zero value is interpreted as false, any non-zero value is interpreted as true.
Real type(float, double, long double). The internal representation of real quantities consists of two things - the mantissa and the order. For example, 148.35 can be represented as 1.4835*10 2, where 1.4835 is the mantissa, 2 is the order. Mantissa >1 and< 2. Длинна мантиссы определяет точность числа, а длина порядка его диапазон. Для float отводится 4 байта = 1 знак + 8 порядок + 23 мантисса). Так как старшая цифра мантиссы =1, то она не хранится. Для double отводится 8 байт = 1 знак+11 порядок+52 мантисса. Константы вещественного типа по умолчанию имеют тип double. Для его изменения можно использовать суффиксы F,f,L,l.
type void is a special type, the set of values of this type is empty. It is not used when describing variables.
In addition, I use the specifier typedef You can enter convenient descriptions for complex types. For example,
typedef unsigned char UC;
UC symbol; // symbol this type variable UC, that is, unsigned character
Let's continue to consider the syntax for describing variables:
[memory class]type name1 [initial_expression1], name2 [initial_expression2],...;
In order to understand what it is memory class Let us introduce several definitions.
Each program object, in particular a variable, is characterized by such parameters as
Scope;
Area of visibility;
Lifetime (duration of existence).
Scope is a part of a program in which an identifier can be used to access a variable. If a variable is declared inside a block, then it is called local and its scope from the point of description to the end of the block. If a variable is declared outside the block, then the variable is called global and its scope is from the point of description to the end of the file.
Area of visibility- this is the part of the program from which it is possible ordinary variable access. Most often, the scope of visibility coincides with the scope of action, but there are exceptions - if variables with the same names are used in nested blocks (the external variable is invisible in this case).
#include
( cout< cout< cout<<::a; The variable name must be unique within its scope. Duration of existence can be constant (static) (the variable exists in memory during the execution of the program), local (the variable exists during the execution of the block in which it is described) and dynamic (such variables are created and destroyed using explicit statements during program execution). Memory class determines the placement of objects in memory, the lifetime, and the scope of a variable. To specify it, the following specifiers are used: auto– automatic variable (memory is allocated on the stack, lifetime - from the moment of description until the end of the block, for local ones this specifier is valid - by default, for global ones - not used); extern- external variable means that the variable is defined elsewhere in the program (another file or lower), available in all program modules where they are described; static– static variable. The lifetime is constant. They can be both local and global. In this case, a global static variable can only be used within the module where it is defined. register– similar to auto, but memory is allocated whenever possible in processor registers (otherwise treated as auto). If the class is not specified explicitly, it is determined by the compiler based on the context of the variable description. Initial_expression– an optional initializer that specifies the initial value of the corresponding object. Variable initializer syntax: Initial_expression (init_expression). For example, int a=10, c(11); If there is no initializing value, then global and static variables are assigned a null value of the corresponding type; automatic variables are not initialized. If the type of the initializing expression does not match the type of the variable, then it is converted according to certain rules (see reference books). For example, char sim=0x61; cout< bool f=10; cout< You can also convert types explicitly: (name of the type to which we convert) variable name the name of the type to which we are converting (variable name). For example, char ch='a'; cout<< (int) ch; или cout << int (ch);// на экране появится ASCII-кода символа a Valid implicit type conversions must be used with great care. Optional modifier const indicates that the value of the variable cannot be changed. If the description specifies a modifier const, then the presence of an initializing expression is mandatory. That is, writing const int a; The description of a variable is performed in the program in the form of a declaration or definition (here in the literature there is also confusion of concepts). Announcement informs the compiler about the variable type and memory class, and when definition Memory is allocated for a variable according to its type. A variable can be declared multiple times, but defined only once. In most cases, the declaration is also a definition. A declaration is not a definition if Contains the extern specifier; Describes the name of the user-supplied type; Describes the function prototype; Describes the name of the class; Describes a static class component. Based on the basic types you can enter derived types: links, pointers, enumerations, arrays, functions, structures, unions, classes. Pointers, references and enumerations, along with arithmetic types and logical types, are classified as scalar, and the rest as structured. Representations play their role in the life of each person - for some people visual representations predominate, for others - auditory representations, for others - motor representations. People differ from each other in the role that representations play. Depending on the predominant type of ideas, they are divided into 4 groups. In addition to the three groups mentioned above, there is a group of people with mixed types of ideas. If past perceptual experience underlies ideas, then the main classification of ideas is based on the classification of types of sensation and perception. Based on this, the following types of representations are distinguished: This is not a single approach to the classification of representations; for example, B.M. Teplov believes that the classification of representations can be presented according to the following criteria: In some cases, visual representations can be very specific and convey all the visible qualities of a particular object - its color, shape, volume. In all other cases of visual representations, one quality will predominate, while others may be absent. As a rule, visual representations do not have three-dimensionality and are reproduced in the form of a two-dimensional picture, which can be either colorful or colorless. The nature of visual representations depends on the content and practical activity during which they arise. For example, in the process of drawing, artists develop vivid, detailed and stable visual images. In order to transfer this visual image to paper, representation is necessary, so they can be superimposed on sensations and combined with them. The artist combines an imaginary image with a sheet of paper. Representation is classified as a cognitive mental process, so it plays an important role in education. The assimilation of any material is associated with visual representations, for example, in geography lessons, a student imagines the natural zone or sea area in question; in physical education lessons, he imagines the action that needs to be carried out, etc. Visual memory images in people who have lost their vision at an early age will be few in number. They reflect only those objects and phenomena that caused strong emotional experiences in them. Auditory representations include speech and musical representations. Speech representations include phonetic and timbre-intonation. Representations of a word without reference to intonation or sound coloring are phonetic representations. Here we are talking about the representation of “the word in general.” Representations are timbre-intonation, associated with the timbre of the voice, with the intonation features of a particular person. Concepts of this kind are very important for a number of professions - actors, teachers, etc. Such auditory representations as musical ones are a representation of a sequence of sounds, their relationship to each other in height and duration, in rhythm. Of course, musical performance will be very well developed among composers and musicians who are able to imagine the sound of an entire orchestra of instruments. Motor ideas include images of movements of varying degrees of complexity. They are always associated with real sensations and muscle tone. Any motor performance, as experiments have shown, is accompanied by muscle contraction. If, for example, you imagine that you are bending your arm at the elbow, then the devices record the contraction occurring in the biceps. Moreover, even a mentally spoken word leads to contraction in the muscles of the tongue, lips, and larynx. It turns out, therefore, that the entire human body is a model of itself. The material basis of motor ideas is weak motor sensations. Motor representations can be divided into groups: The first two types are differently called visual-motor, the third type is auditory-motor. More complex are the ideas about the movement of the whole body, in comparison with individual parts of the body. All main types of representations are to some extent related to each other, so dividing them into classes and types is very arbitrary. Spatiotemporal representations were separated into a separate group. This is because they clearly represent the spatial form and placement of objects, changes in shape and placement over time. With this representation, objects can be presented schematically and colorlessly, so the concept of “visual image” is not applicable to them. You can call them “schematic representations”. Basically, these representations are visuomotor, which are based on visual and motor representations. Spatiotemporal concepts are typical for chess players who calculate different options for the development of the game. They are also typical for football team coaches presenting attack and defense schemes during a game, and drivers assessing the road situation. When studying physical and technical disciplines, space-time concepts are also very important. Theoretical physicists operate precisely with space-time concepts. There are flat and three-dimensional spatial representations. According to the degree of generalization, ideas are divided into general ones, reflecting the properties of a number of similar objects, and individual ones, based on the observation of one object. According to volitional efforts, they can be involuntary and voluntary. The classification of the main types of representations is shown in the diagram. Basic objects and management techniques of WINDOWS Modern Windows is an operating system that controls the operation of a personal computer. Windows has a user-friendly graphical user interface. Unlike the old DOS operating system with a text interface, Windows does not require knowledge of operating system commands and their precise input from the keyboard. The vast majority of operations to control the operation of a personal computer are performed with the mouse over graphical Windows objects, or with short key combinations (hot keys) on the keyboard. User interface– these are methods and means of human interaction with computer hardware and software. Desktop is a graphical environment that displays Windows objects and controls. On the desktop you can see icons (icons), shortcuts, and the taskbar (the main control element). When Windows starts, there are at least three icons on the desktop: My Computer, Network Places, Recycle Bin. There may be other icons on the desktop. It can also be used as a temporary storage for your files, but after finishing work in the classroom, they should either be deleted or moved to their own folders. Badges are a graphic representation of objects and allow you to manage them. Icon -
This is a graphical representation of an object in a collapsed form, corresponding to a folder, program, document, network device or computer. Icons, as a rule, have labels - inscriptions that are located under them. Left-clicking on an icon allows you to select it, and double-clicking it opens (launch) the application corresponding to this icon. Label is a pointer to an object. A shortcut is a special file that contains a link to the object it represents (information about the location of the object on the hard drive). Double-clicking on a shortcut allows you to launch (open) the object it represents. Deleting it does not erase the object itself, unlike deleting an icon. The advantage of shortcuts is that they provide quick access to an object from any folder without using up memory. You can distinguish a shortcut from an icon by the small arrow in the lower left corner of the icon. Task bar is a tool for switching between open folders or applications. On the left side of the taskbar is the Start button; on the right is the display panel. The panel itself displays all currently open objects. Start button opens Main menu. With its help, you can launch all programs registered in the operating system, gain access to all operating system configuration tools, search and help systems, and other functions. The central concept of Windows is the window. Window– a structural and control element of the user interface, which is a rectangular area of the screen limited by a frame in which an application, document or message can be displayed. The picture above shows a Windows desktop with the Main Menu open, the Word word processor window, icons and shortcuts, and some documents minimized on the taskbar. Among other Windows concepts, the concepts of directory and folder should be noted. Catalog– a named group of files united by some characteristic. Folder is a concept that is used in Windows instead of the directory concept in earlier operating systems. The concept of folder has an expanded interpretation, since, along with regular directories, folders also represent objects such as My Computer, Explorer, Printer, Modem, etc. A typical folder window is shown in the figure. The window contains the following required elements. The file system provides storage and access to files on disk. The principle of organizing the file system is tabular. The disk surface is considered as a three-dimensional matrix, the dimensions of which are the surface, cylinder and sector numbers. Under cylinder means the collection of all tracks belonging to different surfaces and equidistant from the axis of rotation. Data about where a particular file is written is stored in the system area of the disk in a special file allocation table ( FAT table). The FAT table is stored in two copies, the identity of which is controlled by the operating system. OS MS-DOS, OS/2, Windows-95/NT implement 16-bit fields in FAT tables. This system was called FAT-16. Such a system allows you to place no more than 65536 records about the location of data storage units. The smallest unit of data storage is sector. The sector size is 512 bytes. Groups of sectors are conditionally combined into clusters, which are the smallest unit of data addressing. The cluster size depends on the disk capacity: in Fat-16, for disks from 1 to 2 GB, 1 cluster occupies 64 sectors or 32 KB. This is irrational, since even a small file takes up 1 cluster. Large files that span multiple clusters end up with an empty cluster at the end. Therefore, the capacity loss for disks in a FAT-16 system can be very large. With disks over 2.1 GB, FAT-16 does not work at all. Windows 98 and older versions have a more advanced file system - FAT-32 with 32-bit fields in the file allocation table. It provides a small cluster size for large capacity disks. For example, for a disk up to 8 GB, 1 cluster occupies 8 sectors (4 KB). File is a named sequence of bytes of arbitrary length. Before the advent of Windows 95, the generally accepted file naming scheme was 8.3 (short name) - 8 characters for the actual file name, 3 characters for the extension of its name. The disadvantage of short names is their low content. Starting with Windows 95, the concept of a long name (up to 256 characters) was introduced. It can contain any characters except nine special ones: \ / : * ? "< >
|. Name extension All characters after the last dot are counted. In modern operating systems, the name extension carries important information about the file type to the system. File types are registered and associate the file with the program that opens it. For example, the MyText.doc file will be opened by the Word word processor, since the .doc extension is usually associated with this application. Typically, if a file is not associated with any opening program, then a flag is indicated on its icon - the Microsoft Windows logo, and the user can specify the opening program by selecting it from the list provided by the OS. Logically, the file structure is organized according to a hierarchical principle: folders of lower levels are nested within folders of higher levels. The top level of nesting is the root directory of the disk. The terms "folder" and "directory" are equivalent. Each file directory on the disk corresponds to an operating system folder of the same name. However, the concept of a folder is somewhat broader. So in Windows 95 there are special folders that provide convenient access to programs, but which do not correspond to any directory on the disk. File attributes- these are parameters that define some properties of files. To access a file's attributes, right-click on its icon and select the Properties menu. There are 4 main attributes: "Read-Only", "Hidden", "System", Archive". The "Read-Only" attribute suggests that the file is not intended to be modified. The "Hidden" attribute indicates that this file should not be display on the screen when performing file operations. The “System” attribute marks the most important OS files (as a rule, they also have the “Hidden” attribute). The “Archive” attribute is associated with file backup and has no special meaning. Copy and move 1 way. Place two windows on the desktop: a copy source and a copy destination. Select the required icons in the source window. Several icons are highlighted when the Ctrl key is pressed. Drag the selected icons into the destination window with the mouse, pointing at any of the selected icons. When the Ctrl key is pressed simultaneously, copying occurs; without it, elements are moved (provided that the folders are on the same disk). Method 2. Select the elements to be copied. Select the Edit/Copy (Cut) menu. Selecting "Cut" will cause movement. Open the destination folder. Select the Edit/Paste menu. Deleting files and folders Deleting files is done by selecting elements and pressing the Delete key. In this case, the marked items are moved to a special folder - Trash. Emptying the Recycle Bin destroys files. There is also an operation for erasing files, when special utilities fill the clusters that contained the erased files with random data. Group operations with files If you need to perform a copy or delete operation on a large number of files at the same time, then selecting them while holding Ctrl is not very convenient. You can select a whole group of consecutive icons by clicking on the first one and, while holding down the Shift key, on the last one. However, in this case, you need to arrange the icons in a certain way. To do this, open the folder with the files and go to the View/Arrange Icons menu. There are 4 ways to organize icons in a folder: by name, by type, by size, by date. For example, you need to copy all files with the extension .txt. In this case, you should organize the icons by type, after which all files of type .txt will be grouped together and use the Shift key to select them. A similar technique is used to select “old” files (organized by date), “small” files (organized by size) and in other standard situations. If the window does not show complete information about the files (extension, size and creation date), you should go to the View/Table folder window menu and the window will display all the characteristics of the files. Renaming files and folders. Renaming a file or folder is performed either through the Rename menu, called up by right-clicking on the corresponding icon, or by clicking on the name of the selected icon. Comment. Deleting or renaming is not possible if the specified file is already open by an application. Windows OS creates and maintains a special area of memory called the clipboard. The clipboard is used to exchange data between Windows applications. The second copying method described above involves using the clipboard. In the Edit menu, for operations with the clipboard, use the Copy, Cut and Paste items. The first two place an object on the clipboard, the last one copies it from the clipboard. If an object (part of text, picture, etc.) is not selected, then the first two items will not be active. If the clipboard is empty, then the third item will not be active. Operations with the clipboard are performed very often, so quick access buttons are placed on the window toolbar. The fastest way to work with the clipboard is to use key combinations: Ctrl+C - copy; Ctrl+X - cut; Ctrl + V - paste.Visual representations
Auditory representations
Motor representations
Spatiotemporal representations
The Windows Start screen is a system object called the desktop. Folder window structure
File system of a personal computer
Operations with files and folders
Working with the clipboard
Control questions
Loading...
