C# 101

01_hello_world.cs

using System;

class Program {
    static void Main(string[] args) {
        var name = "Microsoft";
        Console.WriteLine($"Hello, {name}!");
    }
}

02_string_length.cs

using System;

class Program {
    static void Main(string[] args) {
        var name = "Microsoft";
        Console.WriteLine($"The name `{name}` has {name.Length} letters.");
    }
}

03_string_trim.cs

using System;

class Program {
    static void Main(string[] args) {
        var name = "         Microsoft       ";
        Console.WriteLine($"Hello, {name.TrimStart()}!");
        Console.WriteLine($"Hello, {name.TrimEnd()}!");
        Console.WriteLine($"Hello, {name.Trim()}!");
    }
}

04_string_replace.cs

using System;

class Program {
    static void Main(string[] args) {
        var name = "Microsoft";
        Console.WriteLine($"Hello, {name.Replace("Micro", "Macro")}!");
    }
}

05_searching_string.cs

using System;

class Program {
    static void Main(string[] args) {
        var name = "Microsoft";
        Console.WriteLine(name.Contains("soft"));
        Console.WriteLine(name.StartsWith("Micro"));
        Console.WriteLine(name.EndsWith("t"));
    }
}

06_numbers.cs

using System;

class Program {
    static void Main(string[] args) {   
        // Basic operations
        int a = 18;
        int b = 6;
        int c = a + b;
        Console.WriteLine(c);
        Console.WriteLine(a + b * c);
        Console.WriteLine((a + b) / c);
        Console.WriteLine();

        // Shorts
        Console.WriteLine($"The range of shorts is {short.MinValue} to {short.MaxValue}");
        Console.WriteLine();
        
        // Integer range
        int min = int.MinValue;
        int max = int.MaxValue;
        Console.WriteLine($"The range of integers is {min} to {max}");
        Console.WriteLine($"An example of overflow: {max + 1}, {max + 2}, {max + 3}");

        // Long range
        Console.WriteLine($"The range of longs is {long.MinValue} to {long.MaxValue}");
        Console.WriteLine();
        
        // Modulo operator
        var number = 170;
        var digit = (number/10) % 10;
        Console.WriteLine($"The second digit of {number} is {digit}");

        // Doubles
        double first = 5;
        double second = 4;
        double third = 2;
        double result = (first + second) / third;
        Console.WriteLine(result);
        Console.WriteLine($"The range of doubles is {double.MinValue} to {double.MaxValue}");

        // Decimals
        Console.WriteLine($"The range of decimals is {decimal.MinValue} to {decimal.MaxValue}");
        // `M` is a suffix needed for decimals
        decimal dividend = 1.0M;
        decimal divider = 3.0M;
        decimal decResult = dividend / divider;
        Console.WriteLine(decResult);
        Console.WriteLine();

        // Math
        double radius = 2.5;
        double area = Math.PI * radius * radius;
        Console.WriteLine(area);
    }
}

07_new_console_template.cs

// See https://aka.ms/new-console-template for more information

const int a = 5;
const int b = 6;

const bool result = (a + b > 10);

if (result)
    Console.WriteLine("The answer is greater than 10.");

08_loops.cs

// while loop
var counter = 0;
while (counter < 10)
{
    Console.WriteLine(counter);
    counter++;
}

// do..while loop
do
{
    Console.WriteLine("At least once");
} while(counter < 10);

// for loop
var sum = 0;
for (var i = 0; i < 10; i++)
{
    if (i % 2 == 0)
    {
        sum += i;
        Console.WriteLine($"{i} is an even number");
    }
}
Console.WriteLine($"The sum of even numbers is {sum}");

09_lists.cs

// defining a list
var names = new List<string>{"<name>", "Anna", "Maksim", "Maria"};

// adding and removing items
names.Add("Daniel");
names.Remove("Maksim");

// iterating over the list
foreach (var name in names) {
    Console.WriteLine($"Hello, {name.ToUpper()}");
}
// vs
for (var i = 0; i < names.Count; i++)
{
    Console.WriteLine($"Hello, {names[i].ToUpper()}");
}

// working with indexes
Console.WriteLine(names[0]);
Console.WriteLine($"Found Maria at {names.IndexOf("Maria")}");

if (names.IndexOf("Bill") == -1)
    Console.WriteLine($"Bill is not found");

// in-place sorting
names.Sort();

// Lists of other types ------------------------------------------------------------------

var fibonacciNumbers = new List<int>{1,1};

for (var i = 1; i < 19; i++)
{
    var nextNumber = fibonacciNumbers[i - 1] + fibonacciNumbers[i];
    fibonacciNumbers.Add(nextNumber);
}

var fibonacciSequence = string.Join(", ", fibonacciNumbers);
Console.WriteLine($"The first 20 numbers in the Fibonacci sequence: {fibonacciSequence}");

10_classes.cs

// BankAccount.cs
using System.Text;

namespace CSharp101;

public class BankAccount
{
    public string Number { get; }
    public string Owner { get; set; }

    public decimal Balance
    {
        get
        {
            return _transactions.Sum(transaction => transaction.Amount);
        }
    }

    private static int _accountNumberSeed = 1234567890;
    private readonly List<Transaction> _transactions = new();

    public BankAccount(string name)
    {
        this.Number = _accountNumberSeed.ToString();
        _accountNumberSeed++;
        
        this.Owner = name;
    }

    public void MakeDeposit(decimal amount, DateTime date, string note)
    {
        if (amount <= 0)
            throw new ArgumentOutOfRangeException(nameof(amount), "Amount of deposit must be positive");

        var deposit = new Transaction(amount, date, note);
        _transactions.Add(deposit);
    }

    public void MakeWithdrawal(decimal amount, DateTime date, string note)
    {
        if (amount <= 0)
            throw new ArgumentOutOfRangeException(nameof(amount), "Amount of deposit must be positive");

        if (Balance - amount < 0)
            throw new InvalidOperationException("Not sufficient funds for this withdrawal");

        var withdrawal = new Transaction(-amount, date, note);
        _transactions.Add(withdrawal);
    }

    public string GetAccountHistory()
    {
        var report = new StringBuilder();
        report.AppendLine("Timestamp\t\t\tAmount\tNote");
        foreach (var transaction in _transactions)
        {
            report.AppendLine($"{transaction.Date}\t{transaction.Amount}\t{transaction.Notes}");
        }

        return report.ToString();
    }
}

// Transaction.cs
// namespace CSharp101;

public class Transaction
{
    public decimal Amount { get; }
    public DateTime Date { get; }
    public string Notes { get; }

    public Transaction(decimal amount, DateTime date, string notes)
    {
        this.Amount = amount;
        this.Date = date;
        this.Notes = notes;
    }
}

// Program.cs

var account = new BankAccount("Andrey");
Console.WriteLine($"Account {account.Number} was created for {account.Owner} with ${account.Balance}");

account.MakeDeposit(1000, DateTime.Now, "Initial Balance");
account.MakeWithdrawal(10, DateTime.Now, "Buying a coffee");

try
{
    account.MakeDeposit(-100, DateTime.Now, "XBOX");
}
catch (ArgumentOutOfRangeException e)
{
    Console.WriteLine("Exception caught making a deposit with a negative amount");
    Console.WriteLine(e);
}

Console.WriteLine(account.GetAccountHistory());
Console.WriteLine("------------------------------------------------");
Console.WriteLine($"Current balance: {account.Balance}");