1. Introduction
Programming requires new universal algorithmic models, and hardware implements algorithms not only in a different form, but also on the basis of a different algorithmic model - automata. Borrowing technology from hardware development is the key idea behind automata programming. However, digital device synthesis is different from programming. But when borrowing a model, on the one hand, it is not advisable to change it significantly, and, on the other hand, one cannot ignore the already existing theory and practice of programming.Next, we will look at the SWITCH technology for designing automata programs, in which you encounter similar processes all the time. On the one hand, it changed the finite state machine model so much that it actually took it beyond the scope of automata theory. And, on the other hand, it introduces concepts into programming that are difficult for programmers to perceive, and, at times, are simply superfluous, because there are more familiar analogues from program theory and programming practice.
As a basis for discussing the problems of automatic programming, we will take the recent lecture by Shalyto A.A. and his “programming” articles towards the definition of the automatic programming paradigm.
C++ programming language
Last update: 08/28/2017
The C++ programming language is a high-level compiled programming language general purpose statically typed, which is suitable for creating a wide variety of applications. Today, C++ is one of the most popular and widespread languages.
It has its roots in the C language, which was developed in 1969-1973 at Bell Labs by programmer Dennis Ritchie. In the early 1980s, Danish programmer Bjarne Stroustrup, then working at Bell Labs, developed C++ as an extension to the C language. In fact, in the beginning, C++ simply supplemented the C language with some object-oriented programming capabilities. And that’s why Stroustrup himself initially called it “C with classes.”
Subsequently new language began to gain popularity. New features were added to it that made it not just an addition to C, but a completely new programming language. As a result, “C with classes” was renamed to C++. And from then on, both languages began to develop independently of each other.
C++ is a powerful language, inheriting rich memory capabilities from C. Therefore, C++ often finds its use in system programming, in particular, when creating operating systems, drivers, various utilities, antiviruses, etc. By the way, Windows OS is mostly written in C++. But only system programming application of this language not limited. C++ can be used in programs of any level where speed and performance are important. It is often used to create graphic applications, various application programs. It is also especially often used to create games with rich, rich visualization. In addition, recently the mobile direction has been gaining momentum, where C++ has also found its application. And even in web development, you can also use C++ to create web applications or some supporting services that serve web applications. In general, C++ is a widely used language in which you can create almost any type of program.
C++ is a compiled language, which means that the compiler translates source in C++ executable file, which contains a set of machine instructions. But different platforms have their own characteristics, so compiled programs cannot simply be transferred from one platform to another and run there. However, at the source code level, C++ programs are largely portable unless some OS-specific functions are used. And the availability of compilers, libraries and development tools for almost all common platforms allows you to compile the same C++ source code into applications for these platforms.
Unlike C, the C++ language allows you to write applications in an object-oriented style, representing a program as a collection of classes and objects interacting with each other. Which simplifies the creation of large applications.
Main stages of development
In 1979-80, Bjarne Stroustrup developed an extension to the C language - "C with Classes". In 1983 the language was renamed C++.
In 1985, the first commercial version of the C++ language was released, as well as the first edition of the book "The C++ Programming Language", which represented the first description of this language in the absence of an official standard.
Was released in 1989 a new version C++ 2.0 language, which included a number of new features. After this, the language developed relatively slowly until 2011. But at the same time, in 1998, the first attempt was made to standardize the language by the ISO organization (International Organization for Standardization). The first standard was called ISO/IEC 14882:1998, or C++98 for short. Subsequently, in 2003, a new version of the C++03 standard was published.
In 2011 it was published new standard C++11, which contained many additions and enriched the C++ language with a large number of new functionality. Following this, a small addition to the standard, also known as C++14, was released in 2014. And another key release of the language is scheduled for 2017.
Compilers and development environments
To develop programs in C++, you need a compiler - it translates the source code in C++ into an executable file, which you can then run. But at the moment there are many different compilers. They may differ in various aspects, in particular in the implementation of standards. A basic list of compilers for C++ can be found on Wikipedia. It is recommended for development to choose those compilers that are developing and implement all the latest standards. Thus, throughout this tutorial we will primarily use the freely available g++ compiler developed by the GNU Project.
You can also use IDEs such as Visual Studio, Netbeans, Eclipse, Qt, etc. to create programs.
Learning the basics and intricacies of the C++ programming language. A textbook with practical tasks and tests. Do you want to learn to program? Then you are in the right place - here is free programming training. Whether you're experienced or not, these programming lessons will help you get started creating, compiling, and debugging C++ programs in a variety of development environments: Visual Studio, Code::Blocks, Xcode, or Eclipse.
Lots of examples and detailed explanations. Perfect for both beginners (dummies) and more advanced ones. Everything is explained from scratch to the very details. These lessons (200+) will give you a good base/foundation in understanding programming not only in C++, but also in other programming languages. And it's absolutely free!
Also considered step by step creation games in C++, the SFML graphics library and more than 50 tasks to test your skills and knowledge in C++. An additional bonus is.
For reposting +20 to karma and my gratitude!
Chapter No. 0. Introduction. Beginning of work
Chapter No. 1. C++ Basics
Chapter No. 2. Variables and basic data types in C++
Chapter No. 3. Operators in C++
Chapter No. 4. Scope and other types of variables in C++
Chapter No. 5. The order in which code is executed in a program. Loops and branches in C++
Computers are perhaps the most versatile tools that humanity has at its disposal. They are capable of performing incredible calculations, they allow you to store a huge amount of information, completely different parts of the planet, and at the same time easily exchange it, regardless of location. Computers make many everyday tasks easier, and they make it possible to automate many routine processes that would be very tedious and boring for a human to do. There are so many things that computers can do, but nevertheless, computers do not have intelligence, unlike humans. To automate even the simplest process, you need to tell the computer clearly and unambiguously what exactly it should do. Unfortunately, our language and the computer language are completely different. Thus, between the machine and the person there is a serious language barrier that must be overcome somehow, otherwise the computer will not understand us. And as long as computers don’t understand us, they won’t do anything on their own. A huge number of programming languages have been invented as a means of communication between a person and a computer. With the help of programming languages, we create programs and the computer directly works with the programs. Programs themselves are sets of instructions that a computer can understand and execute.
Types of programs
In order to communicate effectively with the computer, which is what we want, there is a wide range of programming languages.
Depending on the type of project, there are many factors to consider when choosing a programming language. Here is a list of the most notable factors:
Compilation, interpretation and JIT compilation
The compilation process translates code written in a programming language into the native language of the target machine. The program that performs this process is called a compiler. Compilation can make the code run quite quickly, especially if the compiler is efficient at optimizing. But the fact is that the resulting code cannot work on different operating systems, and the compilation process takes some time, and the more code, the longer the compilation process. It is worth noting that when making any changes to the program code, it is necessary to compile it and only then run it.
Interpreted programming languages are read by a program called an interpreter and executed by the same program. Interpreted programming languages can run on different operating systems, just like an interpreter, and do not even have long compilation times. But programs written using interpreted languages tend to run much slower than equivalent, compiled programs.
And finally, the so-called on-the-fly compilation (or JIT compilation). Such languages are quickly compiled at the time the program is launched. Programs written in JIT languages, as a rule, are not optimized, thereby speeding up the compilation process and restoring the balance between performance and cross-platform compatibility.
High or low programming levels
Low-level languages mostly work directly with hardware, and are therefore best suited for writing device drivers. Drivers are programs that control hardware and have direct access to it. However, a program written in a low-level language is usually difficult to port to other platforms. And therefore, for each OS, the same device comes with different drivers. Low-level programming languages almost always compile.
In languages high level the focus is on the concept of language. That is, such a programming language should be easy to understand, such as representing data as arrays, strings, objects, etc. A high-level language is usually easier to understand than a low-level language. And, as a rule, developing a program in a high-level language is much easier and faster than in a low-level language. As you can see, different levels programming programs are designed for completely different tasks, and there is no point in comparing the functionality of languages at different levels, it is pointless.
Programming Language Data Type Systems
For every programming language, there is a specification that defines various rules that programming languages must follow. Some languages don't have data types, so this doesn't apply to them. However, most languages (including C++) have data types, so this information will be useful to you.
Strong or weak data type system
A weak input system does not impose any restrictions; the programmer must monitor this. When I say “weak data system,” I mean that a language with such a data system does not strictly regulate the available data type casts. For example, if you pass a string or symbol instead of a number to the multiplication function, non-strictly typed programming languages will execute such code, although the result of the multiplication loses all meaning, since a string cannot be multiplied by a number. Moreover, the result of performing this meaningless multiplication will be unpredictable. If the programming language is strictly typed, then at the compilation stage, the translator will report an error and stop the process of building the project. For example,
// example program in C++ #include
As a result, the compiler will report an error:
error: invalid operands of types ‘char ’ and ‘int’ to binary ‘operator*’
We will try to do the same in a non-strongly typed programming language - php. Please note that even when declaring variables, you do not need to specify the data type.
The result of executing this code will be zero. No error will occur, although it would seem that you cannot multiply a string by a number. But in PHP everything is possible. The PHP language compiler will not report an error, the script will work and even produce the result, and if our program consists of 1000 lines of code, then it will be difficult for us to find this error. This is a vivid example of a programming language with a “weak data type system,” that is, the prevention of such absurd operations rests entirely on the shoulders of the programmer.
Defined or undefined data type
This applies to both compiled and interpreted languages. Many languages require explicit definition of the type of variables, so there is no uncertainty, the compiler and interpreter clearly know what to do. Some programming languages do not require explicit definition of the type of variables. The data type is determined automatically based on the contents of the variable.
Static or dynamic data type
If the language is statically typed, then the compiler/interpreter does type checking once before the compilation/interpretation process. If the data type is dynamic, then the data types are checked at run time.
Safe or unsafe data type system
There may be situations that may lead to unexpected results or errors. A safe language will introduce as many restrictions as possible to ensure that such situations do not arise. While an unsafe language places all responsibility on the programmer.
These factors can characterize either one or several programming languages.
Supported programming paradigms
Programming paradigms are methodologies or ways of programming that a programming language supports. Here is a list of the main paradigms:
Declarative paradigm
A declarative programming language will place more emphasis on the goal rather than the means to achieve that goal. It is enough to indicate what needs to be achieved, but it is not necessary to indicate what means to use. This paradigm prevents unwanted side effects that can occur when writing your own code.
Functional paradigm
Functional programming is a subset of declarative programming that attempts to solve problems in terms of mathematical equations and functions. Functional programming treats variables and objects as data that is not shared, unlike imperative languages.
Generalized paradigm
Generic programming focuses on writing algorithms in terms of data types to be defined. That is, the same algorithm can work with different types of data. This approach can be a very powerful tool, but only if implemented well.
Imperative paradigm
Imperative languages allow programmers to give the computer an ordered list of instructions that are needed to complete a task. Imperative programming languages are contrasted with declarative programming languages.
Structural paradigm
Structural programming languages aim to provide some form of code—a hierarchical structure. When the structure of the code is clearly visible, the order in which the statements are executed becomes intuitively clear. Such languages usually discourage “jumping” from one part of the code to another, for example, the goto operator we all know, which is defined in the C and C++ languages.
Procedural paradigm
Procedural programming language refers to structured programming languages that support the concept of a procedure or subroutine.
Object-oriented paradigm
Object-oriented programming (sometimes abbreviated OOP) is a subset of structured programming that expresses programs in terms of "objects". This paradigm allows code to be reused, and this approach is quite simple to understand.
Standardization
Do languages have an official standard? Standardization is very important to ensure conflict-free understanding of the program by different compilers/interpreters. Some languages are standardized by the American National Standards Institute (ANSI), others are standardized by the International Organization for Standardization (ISO). All programming languages must be standardized, otherwise there will be no agreement on what is correct and incorrect in syntax.
Let's characterize the C++ programming language
Now that we have examined the main characteristics of programming languages, let us determine which factors the C++ programming language satisfies.
C++ is an ISO standardized programming language.
For some time, C++ did not have an official standard, however, since 1998, C++ has been standardized by an ISO committee.
C++ compiled language.
C++ compiles directly to machine code, making it one of the world's fastest languages.
C++ is a strongly typed language.
C++ assumes that the programmer knows what he is doing, and allows an incredible number of possibilities, limited only by imagination.
C++ supports static and dynamic data types.
Thus, data type checking can be done at compile time or at run time. And this once again proves the flexibility of C++.
C++ supports many paradigms.
C++ supports procedural, generic, and object-oriented programming paradigms, and many other paradigms.
C++ is a portable programming language.
As one of the most commonly used languages in the world, and as an open language, C++ has a wide range of compilers that run on a variety of platforms. The C++ Standard Library code will run on many platforms.
C++ is fully compatible with the C language
In C++ you can use C libraries and they will work properly.
The C/C++ Standard Library includes a number of functions for reading and writing to the console (keyboard and monitor). These functions read and write data as a simple stream of characters.
The concept of stream, used in programming, is closely related to the ordinary, everyday understanding of this word. The input stream can be compared to a pipe through which water (information) enters a pool (computer memory), and the output stream can be compared to a pipe through which water leaves the pool. An important feature of this pipe is that data can only move in one direction at a time. Even if the same pipe is used for input and output, this cannot happen at the same time: to switch the flow direction, it must be stopped, some action must be performed, and only then the flow can be directed in the opposite direction. Another feature of the stream is that it almost never runs dry. Sometimes it dries out, but this period cannot be long if the system is functioning normally.
The standard output function printf()
The printf() function is a standard output function. Using this function, you can display on the monitor screen a string of characters, a number, the value of a variable...
The printf() function has a prototype in stdio.h
int printf(char *control string, ...);
If successful, printf() returns the number of characters printed.
The control line contains two types of information: characters that are directly printed to the screen, and format specifiers that specify how the arguments are printed.
The printf() function is a formatted output function. This means that in the function parameters it is necessary to specify the format of the data that will be output. The data format is specified by format specifiers. The format specifier begins with a % character followed by a format code.
Format specifiers:
| %With | symbol |
| %d | integer decimal number |
| %i | integer decimal number |
| %e | decimal number in the form x.xx e+xx |
| %E | decimal number in the form x.xx E+xx |
| %f | |
| %F | decimal floating point number xx.xxxx |
| %g | %f or %e, whichever is shorter |
| %G | %F or %E, whichever is shorter |
| %o | octal number |
| %s | character string |
| %u | unsigned decimal number |
| %x | hexadecimal number |
| %X | hexadecimal number |
| %% | symbol % |
| %p | pointer |
| %n | pointer |
In addition, l and h modifiers can be applied to format commands.
| %ld | print long int |
| %hu | stamp short unsigned |
| %Lf | long double stamp |
In the format specifier, after the % symbol the precision (number of digits after the decimal point) can be specified. The precision is set as follows: %.n<код формата>. Where n is the number of digits after the decimal point, and<код формата>- one of the codes given above.
For example, if we have a variable x=10.3563 of float type and we want to display its value accurate to 3 decimal places, then we should write:
printf("Variable x = %.3f",x);
Result:
Variable x = 10.356
You can also specify the minimum width of the field allocated for printing. If the line or number is larger than the specified field width, then the line or number is printed in full.
For example, if you write:
printf("%5d",20);
then the result will be as follows:
20
Please note that the number 20 was not printed from the very beginning of the line. If you want the unused spaces of the field to be filled with zeros, then you need to put a 0 symbol in front of the field width.
For example:
printf("%05d",20);
Result:
00020
In addition to data format specifiers, the control line may contain control characters:
| \b | BS, bottom |
| \f | New page, page change |
| \n | New line, line feed |
| \r | Carriage return |
| \t | Horizontal tabulation |
| \v | Vertical tab |
| \" | Double quote |
| \" | Apostrophe |
| \\ | Backslash |
| \0 | Null character, null byte |
| \a | Signal |
| \N | Octal constant |
| \xN | Hexadecimal constant |
| \? | Question mark |
Most often you will use the \n character. With this control character you can go to a new line. Look at the example programs and you will understand everything.
Examples of programs.
/* Example 1 */
#include
void main(void)
{
int a,b,c; // Declaration of variables a,b,c
a=5;
b=6;
c=9;
printf("a=%d, b=%d, c=%d",a,b,c);
}
Result of the program:
a=5, b=6, c=9
/* Example 2 */
#include
void main(void)
{
float x,y,z;
X=10.5;
y=130.67;
z=54;
Printf("Object coordinates: x:%.2f, y:%.2f, z:%.2f", x, y, z);
}
Result of the program:
Object coordinates: x:10.50, y:130.67, z:54.00
/* Example 3 */
#include
void main()
{
int x;
X=5;
printf("x=%d", x*2);
}
Result of the program:
x=10
/* Example 4 */
#include
void main(void)
{
printf("\"Text in quotes\"");
printf("\nOxygen content: 100%%");
}
Result of the program:
"Text in quotes"
Oxygen content: 100%
/* Example 5 */
#include
void main(void)
{
int a;
A=11; // 11 in decimal is equal to b in hexadecimal
printf("a-dec=%d, a-hex=%X",a,a);
}
Result of the program:
a-dec=11, a-hex=b
/* Example 6 */
#include
void main(void)
{
char ch1,ch2,ch3;
Ch1="A";
ch2="B";
ch3="C";
Printf("%c%c%c",ch1,ch2,ch3);
}
Result of the program:
ABC
/* Example 7 */
#include
void main(void)
{
char *str="My string.";
Printf("This is %s",str);
}
Result of the program:
This is My line.
/* Example 8 */
#include
void main(void)
{
printf("Hello!\n"); // After printing there will be a transition to a new line - \n
printf("My name is Pavel."); // This will be printed on a new line
}
Result of the program:
Hello!
My name is Pavel.
The standard input function scanf()
The scanf() function is a formatted input function. With its help, you can enter data from a standard input device (keyboard). Input data can be integers, floating point numbers, characters, strings, and pointers.
The scanf() function has the following prototype in stdio.h:
int scanf(char *control string);
The function returns the number of variables that have been assigned a value.
The control string contains three types of characters: format specifiers, spaces, and other characters. Format specifiers begin with the % character.
Format specifiers:
When entering a string using the scanf() function (%s format specifier), the string is entered before the first space!! those. if you enter the string "Hello world!" using scanf() function
scanf("%s",str);
then after entering the resulting string, which will be stored in the str array, will consist of one word “Hello”. THE FUNCTION ENTERS A STRING BEFORE THE FIRST SPACE! If you want to enter strings with spaces, then use the function
char *gets(char *buf);
With the gets() function you can enter full strings. The gets() function reads characters from the keyboard until the newline character (\n) appears. The newline character itself appears when you press enter. The function returns a pointer to buf. buf - buffer (memory) for the input string.
Although gets() is not the topic of this article, let's write an example program that allows you to enter an entire line from the keyboard and display it on the screen.
#include
void main(void)
{
char buffer; // array (buffer) for the input string
Gets(buffer); // enter a line and press enter
printf("%s",buffer); // output the entered string to the screen
}
One more important note! To enter data using the scanf() function, it needs to pass variable addresses as parameters, not the variables themselves. To get the address of a variable, you need to precede the variable name with an & (ampersand). The & sign means taking the address.
What does address mean? I'll try to explain. In the program we have a variable. A variable stores its value in computer memory. So this is the address that we get using & is the address in the computer memory where the value of the variable is stored.
Let's look at an example program that shows us how to use &
#include
void main(void)
{
int x;
Printf("Enter variable x:");
scanf("%d",&x);
printf("Variable x=%d",x);
}
Now let's return to the control line of the scanf() function. Again:
int scanf(char *control string);
The space character on the control string commands one or more spaces to be skipped in the input stream. In addition to the space, a tab or newline character can be perceived. A non-null character indicates that the character is read and discarded.
The separators between the two numbers you enter are space, tab, or newline. The * after the % and before the format code (format specifier) commands the data type to be read, but not assigned to that value.
For example:
scanf("%d%*c%d",&i,&j);
entering 50+20 will set variable i to 50, variable j to 20, and the + character will be read and ignored.
The format command can specify the largest field width to be read.
For example:
scanf("%5s",str);
indicates the need to read the first 5 characters from the input stream. If you enter 1234567890ABC, the str array will only contain 12345, the remaining characters will be ignored. Separators: space, tab and newline - when entering a symbol, they are treated like all other characters.
If any other characters occur in the control string, they are intended to identify and skip the corresponding character. Character stream 10plus20 operator
scanf("%dplus%d",&x,&y);
will assign the value 10 to the variable x, the value 20 to the variable y, and will skip the plus characters because they occur in the control string.
One of the powerful features of the scanf() function is its ability to specify a scanset. The search set defines the set of characters with which the characters read by the scanf() function will be compared. The scanf() function reads characters as long as they appear in the search set. As soon as the character that is entered is not found in the search set, the scanf() function moves to the next format specifier. The search set is defined by a list of characters enclosed in square brackets. The % sign is placed before the opening bracket. Let's look at this with an example.
#include
void main(void)
{
char str1, str2;
scanf("%%s", str1, str2);
printf("\n%s\n%s",str1,str2);
}
Let's enter a set of characters:
12345abcdefg456
The program will display on the screen:
12345
abcdefg456
When specifying a search set, you can also use the hyphen character to specify spacing, as well as the maximum width of the input field.
scanf("%10", str1);
You can also define characters that are not included in the search set. The first of these characters is preceded by a ^. Many characters differentiate between lowercase and uppercase letters.
Let me remind you that when using the scanf() function, you need to pass variable addresses to it as parameters. The code above was written:
char str; // array of 80 characters
scanf("%s",str);
Note that str is not preceded by &. This is done because str is an array and the array name - str is a pointer to the first element of the array. Therefore, the & sign should not be used. We already pass the address to the scanf() function. Well, simply put, str is the address in computer memory where the value of the first element of the array will be stored.
Examples of programs.
Example 1.
This program displays the request "How old are you?:" and waits for data input. If, for example, you enter the number 20, the program will display the line “You are 20 years old.”. When calling the scanf() function, we put an & sign in front of the age variable, since the scanf() function needs variable addresses. The scanf() function will write the entered value to the specified address. In our case, the entered value 20 will be written to the address of the age variable.
/* Example 1 */
#include
void main(void)
{
int age;
Printf("\nHow old are you?:");
scanf("%d",&age);
printf("You are %d years old.", age);
}
Example 2.
Calculator program. This calculator can only add numbers. When you enter 100+34, the program will produce the result: 100+34=134.
/* Example 2 */
#include
void main(void)
{
int x, y;
Printf("\nCalculator:");
scanf("%d+%d", &x, &y);
printf("\n%d+%d=%d", x, y, x+y);
}
Example 3.
This example shows how to set the reading field width. In our example, the field width is five characters. If you enter a string with a large number of characters, then all characters after the 5th will be discarded. Notice the scanf() function call. The & sign does not precede the array name name because the array name name is the address of the first element of the array.
/* Example 3 */
#include
void main(void)
{
char name;
Printf("\nEnter your username (no more than 5 characters):");
scanf("%5s", name);
printf("\nYou entered %s", name);
}
Example 4.
The last example in this article shows how a search set can be used. After starting the program, enter a number from 2 to 5.
/* Example 4 */
#include
void main(void)
{
char bal;
Printf("Your rating is 2,3,4,5:");
scanf("%", &bal);
printf("\nRating %c", bal);
}