Summary of "C# 2025 С НУЛЯ ДО ПРОФИ | СЛИВ ЛУЧШЕГО КУРСА"

Overview

This is a structured summary of the C# course video (auto-generated subtitles). It lists the main concepts taught, key rules and behaviors, step-by-step methodologies used in example programs, and the speakers identified.

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Course & instructor

• The school published a previously paid full C# course on YouTube; they continue to offer paid/mentored programs.
• Main instructor: Valentin Kravchenko.
• Narrator / school representative (unnamed) provided the announcement and course context.

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Intro to programming and C

• A program is a sequence of imperative steps describing how to get a result.
• C# is a compiled, high-level language in the .NET ecosystem.
• Recommended IDE: Visual Studio.
• Program entry point: the Main method — code executes sequentially from Main.

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Setting up Visual Studio and creating a project

1. Download/install Visual Studio Community (examples in the course used 2019/2022).
2. During installation, select needed workloads (e.g., “.NET desktop development”, ASP.NET/web, Game dev with Unity, language packs).
3. Create a new project:
   • Search for “Console Application (.NET)”.
   • Set name and path → Create.
4. If the console template is missing, rerun the Visual Studio installer and add “.NET desktop development”.

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Running console programs

• Console.WriteLine appends a newline. Console.Write does not.
• Run with F5 (debug) or Ctrl+F5 (run without debug — prevents immediate console closing by adding “Press any key to continue”).
• Prevent the console from closing by using Console.ReadKey() or Console.ReadLine() (or run with Ctrl+F5).

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Basic syntax and first program

• Hello World example: Console.WriteLine("Hello World");
• Strings use double quotes ("..."); chars use single quotes ('c').
• Statements end with a semicolon (;).

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Variables and data types

• Declaration vs initialization: declare a variable first, assign a value later if needed.
• Common primitive types:
  • Integer types: byte/sbyte, short/ushort, int/uint, long/ulong. Each has defined ranges; use .MaxValue/.MinValue to inspect.
  • Floating point: float (single) and double (double). Float literals require suffix F (e.g., 5.7F) because literals default to double.
  • char: single character (single quotes).
  • string: sequence of characters (double quotes).
  • bool: true / false, used in conditions.
• Naming conventions:
  • Use descriptive English names (transliteration allowed if needed).
  • Local variables: camelCase (first word lowercase, subsequent words capitalized).
  • No spaces or punctuation; underscores allowed.
  • Avoid one-letter names and private abbreviations.

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Operators and arithmetic behavior

• Standard operators: +, -, *, /, % (modulo).
• Integer division truncates the fractional part (e.g., 5 / 2 → 2). To get fractional results make at least one operand float/double (cast or use a floating literal).
• Operator precedence: multiplication/division/modulo first, then addition/subtraction. Parentheses override precedence.
• Modulo (%) returns the remainder (e.g., 7 % 5 → 2).
• Compound assignments: x += y (equivalent to x = x + y), likewise -=, *=, /=, %= .
• Increment/decrement:
  • Prefix ++x: increments then returns the value.
  • Postfix x++: returns the value then increments.

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Strings: concatenation and interpolation

• Concatenation: "Hello " + name + "!"
• Interpolation (recommended): $"Hello {name}, you are {age} years"
• + can behave as numeric addition or string concatenation depending on operand types and left-to-right evaluation; use parentheses to clarify priorities.

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Type conversion / parsing

• Common conversion helpers: Convert.ToInt32, Convert.ToSingle, Convert.ToDouble, Convert.ToBoolean, Convert.ToString, etc.
• Parsing console input (which returns string): e.g., int age = Convert.ToInt32(Console.ReadLine());
• Invalid conversions throw exceptions — validate input or handle exceptions.

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Console encoding and regional settings

• Non-ASCII I/O (e.g., Cyrillic) may need explicit encoding:
  • Console.InputEncoding = Encoding.Unicode;
  • Console.OutputEncoding = Encoding.UTF8; (or Encoding.Unicode)
• Behavior can be platform-specific and influenced by regional settings.

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Logical operators and compound conditions

• Comparison operators: ==, !=, >, <, >=, <=.
• Boolean logical operators: && (AND), || (OR), ! (NOT).
• The course explained truth tables and analogies; in practice use && and || for boolean logic.

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Conditional control flow

• if (condition) { ... } else { ... }
• else if for multiple mutually exclusive branches.
• switch usage:
  • switch (value) { case "opt1": ... break; case "opt2": ... break; default: ... break; }
  • Multiple case labels may fall through to the same block (e.g., case "Sat": case "Sun": ... break;).

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Loops

• while (condition) { ... } — use when the number of iterations is unknown.
• for (init; condition; iteration) { ... } — use when iterations are known or controlled by a counter.
• break exits the loop immediately.
• continue skips the rest of the current iteration and proceeds to the next.
• Demonstrated uses: repeated input, retry attempts, countdowns, skipping iterations.

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Random numbers

• System.Random: create with new Random(); call r.Next(min, max) (max is exclusive).
• Pitfall: creating Random instances inside a tight loop can yield identical numbers (same seed). Instantiate Random once and reuse it.
• Random is pseudo-random.

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Arrays

• One-dimensional:
  • int[] arr = new int[10]; or int[] arr = {1,2,3};
  • Zero-based indexing: arr[0], arr[1], …
  • Length: arr.Length
• Multi-dimensional (2D):
  • int[,] matrix = new int[rows, cols]; or int[,] matrix = { {1,2}, {3,4} };
  • Access with matrix[i, j] (i in 0..rows-1, j in 0..cols-1).
  • Iterate with nested loops (outer loop for rows, inner loop for columns).
• Arrays are reference types: assigning one array variable to another makes both refer to the same memory.
• To “resize” an array: create a new array, copy old contents, then assign the new array to the variable — or use List<T> for dynamic-size behavior.

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Example programs — methodology & steps

Below are concise step-by-step methodologies used in the course examples.

Hello World and console basics

1. Create console project.
2. Add: Console.WriteLine("Hello World");
3. Run with Ctrl+F5.

Create a console project (Visual Studio)

1. Create Project → search “console” → select .NET Console Application → Next.
2. Name & path → Create.
3. If missing templates, add “.NET desktop development” workload.

Health / armor damage calculation (percent-based)

1. Inputs: Health (int), ArmorPercent (int), Damage (int).
2. Convert percent to fraction carefully to avoid integer division:
   • Use float percentConverter = 100f;
   • actualDamage = Damage * (ArmorPercent / percentConverter) or cast operands to float.
3. newHealth = Health - actualDamage.

Simple store (buy food)

1. Inputs: Money (int), pricePerUnit (int), quantityWanted (int).
2. Check affordability: canPay = Money >= quantityWanted * pricePerUnit.
3. Implement safe subtraction:
   • Money -= (Convert.ToInt32(canPay) * (quantityWanted * pricePerUnit));
   • If canPay == false, subtract zero.
4. Output updated Money and owned items.

Currency exchanger (rubles/dollars)

1. Inputs: rublesBalance (float), dollarsBalance (float), operation choice (string).
2. Example rates: RUB_TO_USD = 64, USD_TO_RUB = 66.
3. If choice == “1” (rubles → dollars):
   • Ask amount; check rublesBalance >= amount.
   • rublesBalance -= amount;
   • dollarsBalance += amount / RUB_TO_USD;
4. If choice == “2” (dollars → rubles): similar logic.
5. Use Convert.ToSingle(Console.ReadLine()) for floats; use switch for operation choice.

Password check & input with attempts

• Password check:
  • Store password string; read user input; compare: if (input == password).
• Retries (e.g., for password attempts):
  1. Use a for loop with attempt counter.
  2. Ask password each iteration.
  3. If correct: reveal secret and break.
  4. Otherwise show attempts left.

Guess-the-number game

1. Random r = new Random();
2. secret = r.Next(0, 101); (0..100).
3. attempts = 5;
4. while (attempts > 0) { attempts--; read guess; if guess == secret → win & break; else continue }
5. If not found after attempts, reveal secret.

Bank deposit compound interest simulation

1. Inputs: initialMoney (float), years (int), percent (float).
2. For each year:
   • money += money * percent / 100;
3. Optionally pause between years with Console.ReadKey().

Simple duel (player vs enemy)

1. Initialize playerHealth, playerDamage, enemyHealth, enemyDamage.
2. while (playerHealth > 0 && enemyHealth > 0) { playerHealth -= enemyDamage; enemyHealth -= playerDamage; }
3. After loop, check outcomes:
   • both <= 0 → draw
   • playerHealth <= 0 → enemy wins
   • enemyHealth <= 0 → player wins

Gladiator randomized fights

1. Randomize attributes for both gladiators (health, damage, armor) using one Random instance.
2. While both alive apply damage accounting for armor:
   • effectiveDamage = damage * (100 - armor) / 100
3. Update health, print statuses, break when one dies, then print result.

Library management (2D array of strings)

1. Store library in string[,] books = { { "Author", "Title" }, ... } or rows/columns layout.
2. Finding by index:
   • Prompt user for 1-based indices → convert to 0-based (index - 1) → print books[row, col].
3. Finding by author:
   • Iterate all rows/columns, compare with ToLower()/ToUpper() for case-insensitive matching.
4. Use a menu (switch) for display, update, exit; guard against invalid inputs.

Arrays resizing (manual)

1. Create a new temp array with length old.Length + 1.
2. Copy elements from old to temp via loop.
3. Set temp[last] = newValue.
4. Assign temp to the original variable.
5. (Alternative: use List<T> for dynamic sizing.)

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Miscellaneous console capabilities

• Console.Clear() — clear console.
• Console.SetCursorPosition(left, top) — position cursor.
• Console.ForegroundColor / Console.BackgroundColor — change colors.
• Console.WindowHeight / Console.WindowWidth — window dimensions.
• Escape sequences: \n for new line (use \\n in literal strings where escaping is needed), other escapes like \b, etc.

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Key gotchas and practical tips

• Integer division truncates fractional parts — cast to float/double when needed.
• Float literals require F (e.g., 5.7F) or an explicit cast when assigning to a float.
• Convert.* methods throw exceptions on invalid input — validate or catch exceptions.
• Instantiate Random once (outside loops) to avoid repeated identical numbers.
• Arrays are reference types — assignment copies the reference, not the elements.
• Use descriptive names in English and stick to naming conventions to aid team collaboration.
• Use string interpolation ($"...") for readable formatted output.
• Use switch for many mutually exclusive discrete options; use if/else if for range checks or simpler branching.

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Speakers / sources (from subtitles)

• Narrator / School representative — course announcement and publishing context.
• Valentin Kravchenko — main instructor, demonstrations, and explanations.

Note: demo names used in examples (Pushkin, Lermontov, Yesenin, Robert Martin, Stephen King, Bram Stoker, etc.) are sample data, not speakers.

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If you want, I can: - Extract step-by-step code snippets for one or more example programs (e.g., Guess-the-number, currency exchanger, deposit calculator). - Create a short C# cheatsheet with the most important syntax shown. - Produce a compact “getting started” checklist for installing Visual Studio and creating your first console app.

Which option would be most helpful?

Category

Educational

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