Download a good text editor. Many programming languages ​​allow the use of external text editors to write programs. Find a text editor that will display indentation and code markup.

• Popular programs include Notepad++ (Windows), TextWrangler (OS X), and JEdit (any system).

Download any necessary compilers. Some programming languages ​​require a compiler to display the source code you have written. Compilers translate source code into an equivalent low-level language program, which is then processed by the computer. Many compilers are open source and free software. Languages ​​that require the use of compilers include:

• BASIC
• Fortran
• Pascal

Start your first project. Choose a good introductory project that will allow you to try out your new skills. There are many offers and tutorials on this topic on the Internet; for example, you can start by creating simple websites with HTML, simple databases and functions with PHP, or simple programs in any of the languages ​​that require the use of compilers.

This is an introductory part devoted to the theoretical foundations of programming. The reader can familiarize himself with it and then move on to studying programming in practice (links at the beginning and end of this material), can turn to practical exercises right away, or can continue to get acquainted with the theory of software development, choosing questions that interest him from the list above. As for this article, here are its main sections:

Advice: When reading further material, do not try to remember all the terms and definitions that appear throughout the story. Everything will fall into place over time, especially since the hypertext of Internet pages is good because links to a detailed presentation of the material can be found where necessary. You can always return to the desired page and do it exactly when you feel a lack of knowledge. If any section is difficult for you to understand, skip it. If you don’t return to it in the future, this means that it turned out to be unnecessary for you in the process of learning the basics of programming.

What is an algorithm, programming and pseudocode

Let's start by defining what an algorithm is. Algorithm is the order of actions that must be performed to solve a specific problem. The concept of an algorithm is not associated only with programs executed on , so the answer to the question “who needs to execute” can be anyone or anything: a person, a robot, computer technology, etc. Algorithm- this is an instruction or guide or, finally, just action program. In this case, it is a description of the algorithm by means of , the constructions of which the computer can process. Or is it simply the process of writing the text of a computer program. In this interpretation, programming is synonymous with coding process. Why did I talk about interpretations? The fact is that software developers are very passionate about what they do, and can be extremely unhappy when their work is reduced to just the process of coding in a specific programming language. Itself is not only coding, but also the preliminary design stage, as well as subsequent stages and maintenance. By programming they often mean the process of creating a computer program as a whole, including the development of an algorithm, and coding is the translation of an already developed algorithm into a language understandable encoding object(meaning a computer or any other device that works according to a program specified by someone).

So, the algorithm for any problem, described in any algorithmic language(procedural programming language), to a first approximation appears as a sequence of instructions or operators. An operator can be simple or compound. Simple operator- this is atomic programming language unit. Simple operators include (defining the name and type of a variable), (assigning a value to a variable), input and output operations, etc.

Variable (in programming) is a named area of ​​RAM intended for temporary storage of a portion of data processed by a computer program. A variable is characterized by the size of the memory it occupies and its type, which determines how the memory is interpreted by the computer. The type of a variable can be simple or complex (complex). Simple types include numeric, character and logical types. A complex type is a collection of simple and/or other composite types.

Compound statements are used to organize other statements in a sequence and control the flow of program execution. Compound operators include (repetition of a sequence of operators), etc. and are not operators themselves. They can be arguments to variable values ​​or criteria for executing loops and conditional statements. Part of mathematical and logical expressions can be .

Subtotals: The simplest computer program is a sequence of operators (program instructions), some of which modify variables, while others control the execution of the program (loops, conditional statements), based on conditions specified by logical and arithmetic expressions.

If any of this raises questions, then I suggest you follow any of the links above and get acquainted with the constructs of the procedural programming language I described in more detail.

Previously, algorithms, before being implemented in , were presented in the form . Today, it seems to me, classical flowcharts are used quite rarely (in schools or in various courses on the basics of programming). Also, flowcharts are used to describe business processes together with diagrams, but this already applies to the stages of macro design. In my practice, I very rarely use any intermediate forms of describing algorithms, but if such a need arises, I do it using pseudocode. Pseudocode- This pseudo programming language, for which there are no standards for syntax. Pseudocode is devoid of details that are insignificant for understanding the essence of the algorithm, without which it is impossible to write programs in real programming languages. The only one the purpose of pseudocode is to formalize the description of the algorithm. Problems whose solutions are described in pseudocode are very easily transferred to any programming language, since pseudocode is a programming language with the only difference that there is no compiler for it, and the only interpreter for it is the human brain. I will tell you what a compiler and interpreter are at the end of this material.

Examples of algorithms in pseudocode and in the form of flowcharts

Here is an example of a description of the algorithm for the problem of dividing one number by another, performed in pseudocode:

A: INTEGER TYPE INPUT(A) B: INTEGER TYPE INPUT(B) IF B=0 THEN OUTPUT(“ERROR: DIVISION BY 0!”) OUTPUT END IF C: REAL TYPE C = A / B OUTPUT(C)

Integrated development environment (IDE) – a set of software tools that offer the user tools for writing program code, searching for and highlighting syntax errors in it, and running the application in debugging mode. The integrated development environment includes a compiler, linker, debugger, profiler, and other components. The most popular environment for developing software products in the programming languages ​​C#, VB.NET and C++ is, and for educational purposes I suggest using the following.

Debugger – an IDE tool that allows you to execute a program step by step and track the values ​​of variables at each step defined by breakpoints or break points.

Profiler – an IDE tool used to optimize program code in terms of its execution speed and the amount of RAM it occupies. Using a profiler, you can collect statistics on which part of the code is executed most often, and how much time and resources the computer spends on its execution. Based on these statistics, you can identify the bottlenecks of your program and direct your efforts to optimize them.

Programming language – a formal language represented by a set of instructions (operators) with the help of which computer programs are written in compliance with a certain syntax. In other words, a programming language is the main tool for implementing an algorithm for a specific task on a computer.

Machine code - a system of commands that the computer processor understands “without translation”.

High and low level programming languages – classification of programming languages ​​according to the degree of ease of their use by humans to solve applied problems (high-level languages) or according to the degree of their proximity to machine code (low-level languages).

Compiler – an application that deals with the compilation process - the translation of a program (translation of program code) written in a high-level programming language into a low-level language or into machine code. Compiling into a low-level language most often means translating a program into assembly language in order to fine-tune individual bottlenecks before finally translating it into machine code. An example of a program in assembler can be seen.

Object module – a file containing the result of the compiler’s work, namely the machine code itself with links to other object modules, if the program is complex and consists of many components.

Linker – an application that enters the process of creating an executable module after the compiler. If the result of compilation is several object modules, then the linker finds them all and builds an executable module from them.

Executable module – a file containing the program exactly in the form that the bootloader of a specific operating system can process. Most often these are files with the extension exe or dll.

Loader - part of the operating system that creates a separate one for the program, loads the data of the executable file into RAM (into the RAM area allocated for the process), initializes the processor registers, and starts the process. From this moment the program begins to execute.

Interpreter – a program that executes program code step by step, translating into machine code only that part of it that needs to be executed at a specific point in time. The interpreter processes the program line by line. The difference between a compiler and an interpreter is that the compiler translates the entire program into machine code at once, creating one or more object modules, and the interpreter, having translated only the fragment of the program it needs, immediately executes this fragment. Thus, some interpreters are a compiler, linker and loader rolled into one. An example of an interpreter is a processing unit in an Internet browser.

Let me finish with the theory and move on to practice. I'll start with this.

Any program or online service, for example, Word, Microsoft Windows, WhatsApp or a browser, which hundreds of millions of people launch every day, one way or another, consists of special instructions. Or special program code that the machine understands and tells it what to do or, conversely, not to do. Or how to properly respond to user actions. What program code is will be discussed in this article.

Description

A program's program code is text written in a special language that a machine can understand. It can be executed directly from the text using an interpreter or translated into a special form using a compiler.

The source code of a program may consist of several files. Moreover, they all must be of the same format. The program text contained in them must be written in the same language. True, there may be exceptions. For example, in web development, a page file may contain several different programming languages ​​and standards. Depending on the complexity of the project, languages ​​and technologies such as PHP, HTML, and others may be present.

When assembled, complex software systems may require a large number of files, which can number in the hundreds. To collaborate on such large projects, programmers very often use version control systems. They allow you to simultaneously work with several copies of source code, which at a certain stage of development can be combined into one common one.

Code quality

The computer is not able to understand how the code for it is written, bad or good. If it is operational and does not contain errors, then the machine will launch it in any case. Bad code can complicate software maintenance tasks. This is especially true for large projects. Typically, high-quality code is characterized by several parameters:

• Code readability. One glance at it should be enough to generally understand what is being implemented by a piece of code.
• The presence of clear and succinct comments. This parameter greatly affects readability, ease of debugging, support testing, and troubleshooting of program code.
• Low difficulty.
• Code optimization. It should be organized in such a way that the program uses as few system resources as possible, such as memory, processor time and hard disk space.
• No trash. That is, unused variables or blocks of code in which program control never enters.

Malicious code

In addition to useful programs, there are some that can harm the system or even the equipment. As a rule, such code is written by people who are interested in some benefit from the ongoing process. For example, programs that can steal personal data from users’ computers. They may be payment card numbers, passport data, or any other confidential information. Others may simply interfere with the operation of the system, thereby causing failures and preventing full functionality.

Jeff Vogel, a longtime programmer, shared some tips for teaching aspiring developers the rules of good code.

In particular, he suggests always commenting your program code. What is a comment? It is a clear and concise description of what is happening in a given line of code or function. The fact is that the development of a certain program may drag on for a month or even stop for some time. Returning to work on a project after a couple of months, even an experienced programmer will find it difficult to understand his own program. But detailed comments will be able to restore the chain of events and the behavior of the code.

He further recommends using global variables in your program as often as possible. This is explained by the fact that when changing the program code, you will have to adjust the value of the variable in just one place. In this case, all functions or procedures that use the value will immediately know about it and will perform operations with the new data.

Variable names and error detection

The correct name of variables will also help to significantly reduce the time spent studying the source code of the program, even if the code was written by yourself. That is, good code is considered to be text where variables and functions have names that make it clear what exactly they do or store. In this case, you should try not to use long variable names.

It is very important to pay great attention to timely elimination of errors. What is program code that executes perfectly? This is code that has no errors. That is, any loop branching or variable change, or even any unexpected user actions, will always lead to the expected result. This is achieved by testing the finished product several times.

Identifying program code errors, or rather, predicting them, is possible at the program design stage. The presence in the code of various checks of conditions and possible exceptions will help control the program along a certain course.

Optimization is of enormous importance for writing a workable program that will economically use computer resources and at the same time avoid errors in program code execution. What is an optimized program? This is a product that is capable of performing all the declared functionality, while behaving “quietly” and economically.

Almost always, optimization for stable program operation can only be achieved by conducting several tests on different platforms and under different conditions. If a program begins to behave unpredictably, you need to determine what caused it and, if possible, eliminate or intercept the process.

Conclusion

What is program code? In simple terms, it is a set of instructions and concepts for a computer. It contains text that a compiler or interpreter can turn into machine-readable language. That is, in essence, program code is an intermediary between a person and a computer, which simplifies their relationship.