CsCodeExample

Examples of c# code in form of a simple tutorial. Containing:

Console Output
Variables
Declaration
Arithmetic Operators
Selection Statements
Iteration Statements
Arrays and Lists
Parsing and Exceptions
Functions
Enum
Classes
Console Input
File Read & Write

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Want to Contact for Development & Consulting: www.codis.tech (Quality Assurance)

Contributing

Please read CONTRIBUTING for details on code of conduct, and the process for submitting pull requests.
When opening issues do write detailed explanation of the problem or feature with reproducible example.

**Also take a look into others packages:
Open source (MIT or cFOSS) authored .Net libraries (@Infopedia.io personal blog post)

№	.Net library	Description
1	EFCore.BulkExtensions	EF Core Bulk CRUD Ops (Flagship Lib)
2	EFCore.UtilExtensions	EF Core Custom Annotations and AuditInfo
3	EFCore.FluentApiToAnnotation	Converting FluentApi configuration to Annotations
4	FixedWidthParserWriter	Reading & Writing fixed-width/flat data files
5	CsCodeGenerator	C# code generation based on Classes and elements
6*	CsCodeExample	Examples of C# code in form of a simple tutorial

Naming Conventions

Local variables - nonCapitalLetter, camelCase.
Class, Function (Method - in a class) and Property name - CapitalLetter, PascalCase.
DO choose easy readable identifier (eg. HorizontalAlignment more English-readable than AlignmentHorizontal).
DO favor readability over brevity (property CanScrollHorizontally better than ScrollableX (obscure X-axis ref).
DO NOT use underscores (Hungarian notation), hyphens, or any other nonalphanumeric characters.
AVOID using identifiers that conflict with keywords of widely used programming languages.

Programming Principles:

DRY - Don't Repeat Yourself
YAGNI - You Aren't Gonna Need It (but have as much as you can out of the box)
KISS - Keep it Simple, Stupid - Kelly Johnson
"Good design is as little design as possible." - Dieter Rams
"Everything should be made as simple as possible, but not simpler." - Albert Einstein
"Complexity is your enemy. Any fool can make something complicated. It's hard to keep things simple."-Richard Branson
"Simple can be harder than complex: You have to work hard to get your thinking clean to make it simple." - Steve Jobs
"I have made this letter longer than usual, only because I have not had the time to make it shorter." - Blaise Pascal
"I have just three things to teach: simplicity, patience, compassion. These three are your greatest treasures." - Lao Tzu

LoD - Law of Demeter or principle of least knowledge
SoC - Separation of Concerns; Layers: presentation, business(service), DAL - data access layer, DB - database
DDD - Domain Driven Design
_ RP - Repository Pattern msdn/TheRepoPattern (allows dependency injection and unit test for EF)
_ DI - Dependecy Injection (IoC - Inversion of Control), loosely-coupled
PRG pattern - Post/Redirect/Get
GRASP - General Responsibility Assignment Software Patterns

OOP - Object Oriented Programming
SOLID (object-oriented design) SolidInPictures:
[S] SRP - Single Responsibility Principle (a class should have only a single responsibility)
[O] OCP - Open/Closed Principle (entities[class, function,..] to be open for extension, closed for modification)
[L] LSP - Liskov Substitution Principle (objects replaceable with subtypes instances without altering correctness)
[I] ISP - Interface Segregation Principle (many client-specific interfaces are better than one general-purpose interface)
[D] DIP - Dependency Inversion Principle (Depend upon abstractions, not upon concretions, Dependency injection)

CODE:

// - LINE COMMENT

/*
SEGMENT COMMENT
*/

// break point(F5, F10), refactor, search and replace, Go to def., Find all ref., (un)comment

#region MyRegion
// your collapsible code here
#endregion

#region Output
Console.Write("OUTPUT:");
Console.WriteLine("Program is running.");

Console.WriteLine();
#endregion

#region Variables
// VARIABLES (local - must be assigned)
// primitive(built in) type / object (value range)
/*
bool    / Boolean   (true, false)                   [default: false]
byte    / Int8      (+- 127)                        [default: 0]
short   / Int16     (+- 32,767)                     [default: 0]
int     / Int32     (+- 2,147,483,647)              [default: 0]
long    / Int64     (+- 9,223,372,036,854,775,807)  [default: 0]
float               (+- 1.5 E−45 to +- 3.40282347 E+38)            [default: 0]  Precision: ~6-9 digits
double              (+- 5.0 E−324 to +- 1.7976931348623157 E+308)  [default: 0]  Precision: ~15-17 digits
decimal / Decimal   (+- 1.0 E-28 to +- 7.9228 E28)                 [default: 0]  Precision: 28-29 digits
char    / Char                                      [default: '']
string  / String                                    [default: null, nullable]
var // can be any type
*/
#endregion

#region Naming Conventions
/*
local variables - nonCapitalLetter, camelCase
Class, Function(Method - in a class) and Property name - CapitalLetter, PascalCase
DO choose easily readable identifier names(exmample HorizontalAlignment more English-readable than AlignmentHorizontal)
DO favor readability over brevity.
The property name CanScrollHorizontally is better than ScrollableX (an obscure reference to the X-axis).
DO NOT use underscores(Hungarian notation), hyphens, or any other nonalphanumeric characters.
AVOID using identifiers that conflict with keywords of widely used programming languages.
*/
#endregion

#region Declaration
// Declaration of variable (camelCase Notation)
bool isAdmin;
int counter;
double sum;
decimal number;
char character;
string name;

// Assignment of variable
isAdmin = true;
counter = 5;
sum = 3.14;
number = 18.65m;
character = 'a';

name = "Ben Benito";

Console.WriteLine("c" + counter);

// Declaration and Assignment
bool isActive = true;

// Nullable (can take all values of its underlying value type and an additional null value)
bool? isEnded = null;
string city = null;
// String is null (and therefore nullable) by default, so there's no need for this notation)

// Cast
int inputAmount = 126;
decimal secondAmount = inputAmount; // implicit cast
int thirdAmount = (int)secondAmount; // explicit cast
string strNum = "1234";
int outputNum = int.Parse(strNum);

Console.WriteLine("DECLARATION");
Console.WriteLine("T or F: " + isAdmin);
Console.WriteLine("Counter: " + counter);
Console.WriteLine("Sum: " + sum);
Console.WriteLine("Number: " + number);
Console.WriteLine("Letter: " + character);
Console.WriteLine("Word or Sentance: " + name);
Console.WriteLine("Active: " + isActive);
Console.WriteLine("Finished: " + isEnded);

// string interpolation
Console.WriteLine("City Name: " + city); // Old way to concatenate strings
Console.WriteLine("City Name: {0}", city);
Console.WriteLine($"City Name: {city}"); // Newest way, from C# 6 version

Console.WriteLine();
#endregion

#region Operators
// Arithmetic Operators
// = + - * / %
int x = 10, y = 6; // Declaration and assignment of multiple variables of the same type at once
int result = x + y;

Console.WriteLine("OPERATORS");
Console.WriteLine("a + b = " + x + " + " + y + " = " + result);
Console.WriteLine("a + b = {0} + {1} = {2}", x, y, result);
Console.WriteLine($"a + b = {x} + {y} = {result}");

x *= 2;
//x = x * 2;

x++;
//x = x + 1;

//x--;
//x = x - 1;

Console.WriteLine("x = x * 2 + 1 = " + x);
Console.WriteLine("r = x++ = " + x++); // output is the value of x BEFORE incrementing
Console.WriteLine("x= " + x);
Console.WriteLine("r = ++x = " + ++x); // output is the value of x AFTER incrementing
Console.WriteLine("x = " + x);
Console.WriteLine("");

// Relation Operators
// == !=  > >= < <=

// Logical Operators
// && AND
// || OR
// !  NOT
#endregion

#region Selection Statements (Conditionals)
Console.WriteLine("SELECTION STATEMENTS (Conditionals)");
// if, else, switch, case

bool print = true;

if (print)
	Console.WriteLine("true - ");

print = false;

if (print)
	Console.WriteLine("false - no output");

if (!print)
	Console.WriteLine("not false = true - output");

int age = 20;
if (age > 18)
	Console.WriteLine("Adult");
else
	Console.WriteLine("Minor");

int value = 23; // value range 0-29
string clause = "Value is from-to: ";

if (value >= 0 && value < 10)
	Console.WriteLine(clause + "0-9");
else if (value >= 10 && value < 20)
	Console.WriteLine(clause + "10-19");
else if (value >= 20 && value < 30)
	Console.WriteLine(clause + "20-29");
else
	Console.WriteLine(clause + "30+");


int mod = value % 3;

if (mod == 1)
	Console.WriteLine("Remainder 1");
else if (mod == 2)
	Console.WriteLine("Remainder 2");
else
	Console.WriteLine("Divisible with 3");

switch (mod)
{
	case 1:
		Console.WriteLine("Remainder 1");
		break;
	case 2:
		Console.WriteLine("Remainder 2");
		break;
	default:
		Console.WriteLine("Divisible with 3");
		break;
}

int? year = null;
// null coalescing operator (??) - returns the value of its left-hand operand if it isn't null; otherwise, it evaluates the right-hand operand and returns its result
Console.WriteLine("Year = " + (year ?? 2017)); // returns 2017, as year == null

string yearType = year % 2 == 0 ? "Even year" : "Odd year"; // (? :) - conditional operator, ternary
// General case:  result = condition ? result if condition is true : result if condition is false;
Console.WriteLine("Year type :" + yearType);

#endregion

#region Iteration Statements
Console.WriteLine("ITERATION STATEMENTS");
// for, while, do, foreach, in

// Jump statements
// break, continue, default, return, (go to)

// Exception handling statements
// throw, try-catch


Console.Write("For loop: ");

for (int i = 1; i <= 5; i++)
	Console.Write(i + " ");

Console.WriteLine("");
Console.Write("While a): ");
// Do - while loop, executes at least once, even if the condition is not fulfilled
int k = 40;
do
{
	k = k * 2;
	Console.Write(k + " ");
} while (k < 20);

Console.WriteLine("");
Console.Write("While b): ");
k = 1;
while (k < 20)
{
	k = k * 2;
	if (k == 8)
		break;
	Console.Write(k + " ");
}

Console.WriteLine("");
Console.Write("While c): ");
k = 1;
while (k < 20)
{
	k = k * 2;
	if (k == 8)
		continue;
	Console.Write(k + " ");
}

Console.Write("\n\n");
#endregion

#region Arrays
Console.WriteLine("ARRAYS");

double[] fiveDayPrices = new double[5]; // fixed size;
fiveDayPrices[0] = 3.45;
fiveDayPrices[1] = 3.55;
fiveDayPrices[2] = 3.58;
fiveDayPrices[3] = 3.30;
fiveDayPrices[4] = 3.32;

Console.Write("Five day prices: ");
for (int i = 0; i < 5; i++)
{
	Console.Write(fiveDayPrices[i] + " ");
}

Console.Write("\nFive day prices backwards: ");
for (int i = fiveDayPrices.Length - 1; i >= 0; i--)
{
	Console.Write(fiveDayPrices[i] + " ");
}

Console.Write("\nForeach: ");
foreach (var element in fiveDayPrices)
{
	Console.Write(element + " ");
}

Console.WriteLine("");

Console.WriteLine("Matrix");
// Multidimensional arrays
// Two-dimensional array. 
int[,] matrix = new int[3, 3]; // fixed size;

matrix[0, 0] = 1;
matrix[0, 1] = 2;
matrix[0, 2] = 3;
matrix[1, 0] = 4;
matrix[1, 1] = 5;
matrix[1, 2] = 6;
matrix[2, 0] = 7;
matrix[2, 1] = 8;
matrix[2, 2] = 9;

for (int i = 0; i < 3; i++)
	for (int j = 0; j < 3; j++)
		Console.Write(matrix[i, j] + " ");

Console.WriteLine();

int[,] matrixB = new int[3, 3]; // fixed size;

for (int i = 0; i < 3; i++)
{
	for (int j = 0; j < 3; j++)
	{
		matrixB[i, j] = (i * 3) + j + 1;
		Console.Write(matrixB[i, j] + " ");
		if ((j + 1) % 3 == 0)
			Console.WriteLine("");
	}
}

// A similar array with string elements. 
string[,] array2Db = new string[3, 2] { { "one", "two" }, { "three", "four" }, { "five", "six" } };

// Three-dimensional array. 
int[,,] array3D = new int[,,] { { { 1, 2, 3 }, { 4, 5, 6 } }, { { 7, 8, 9 }, { 10, 11, 12 } } };


Console.WriteLine("Dif. Matrix");
// Array(Jagged) that can have different row size

// This could be clarified!
int[][] jaggedArray = new int[3][];
for (int i = 0; i < 3; i++)
{
	jaggedArray[i] = new int[(i + 1)];
	for (int j = 0; j < (i + 1); j++)
	{
		jaggedArray[i] = new int[(i + 1)];
		jaggedArray[i][j] = (i * 3) + j + 1;
		Console.Write(jaggedArray[i][j] + " ");
		if ((j + 1) % (i + 1) == 0)
			Console.WriteLine("");
	}
}

// List
List<string> words = new List<string>
{
	"one",
	"two",
	"three",
};
words.Add("four");
words.Add("five");
words.Remove("three");

Console.WriteLine("");
foreach (var word in words)
	Console.Write(word + " ");

Console.WriteLine("\n" + words[1]);
Console.WriteLine(words.ElementAt(1));

List<char> letters = new List<char>() { 'a', 'b', 'c' };

foreach (var letter in letters)
{
	Console.Write(letter + " ");
}
// Dictionary
Dictionary<String, int> accounts = new Dictionary<String, int>
{
	{ "Cash", 110 },
	{ "Receivable", 120 },
	{ "Supplies", 130 },
};
accounts.Add("Insurance", 150);

accounts.TryGetValue("Supplies", out int account);

Console.Write("\nSupplies account: " + account);


List<string> sentences = new List<string>
{
	"I am playing",
	"I play",
	"You are going",
	"You go",
	"He is running"
};
sentences.Remove("He runs");

// Lambda expression =>
IEnumerable<string> ingEndSentences = sentences.Where(a => a.EndsWith("ing")); // EndsWith, Contains
List<string> ingEndSentences2 = sentences.Where(a => a.EndsWith("ing")).ToList(); // EndsWith, Contains

Console.WriteLine("\nING:");
foreach (var sentence in ingEndSentences2)
{
	Console.WriteLine(sentence);
}

List<string> ingEndSentences3 = new List<string>();
foreach (var sentence in sentences)
{
	if (sentence.EndsWith("ing"))
	{
		ingEndSentences3.Add(sentence);
	}
}
#endregion

#region Parsing and Exceptions
Console.WriteLine("\n\nPARSING AND EXCEPTIONS");

string customNumStr = "324erer";
int customNum;
var validNum = int.TryParse(customNumStr, out customNum);
if (validNum)
	Console.WriteLine(customNum);
else
	Console.WriteLine("Parse Error");

try
{
	customNum = Int32.Parse(customNumStr);
}
catch (Exception ex)
{
	Console.WriteLine("Exception:\n" + ex.StackTrace + "\n");
	//throw new Exception("Exception on Parsing string to int.");
}
#endregion

#region Methods
Console.WriteLine("\nMETHODS (Functions)");
// Access Modifiers
//   public    - most accessible
//   protected - in class where declared and all derived classes
//   internal  - within files in the same assembly
//   private   - only in class where declared

// Output: return type(one) - [void = no return], side effects

// Input: arguments

// keyword static - can be called without object instantiation

PrintText("To be printed.");
PrintText("End.");

decimal num1 = 12.3m;
decimal num2 = 2.5m;
int num3 = 3;

decimal quotient = Divide(num1, num2); // num1, num2 are Arguments - values on function call
Console.WriteLine("{0} / {1} = {2}", num1, num2, quotient);

Console.WriteLine("{0} * {1} * {2} = {3}", num1, num2, num3, Multiple(num1, num2, num3));
Console.WriteLine("{0} * {1} = {2}", num1, num2, Multiple(num1, num2));
Console.WriteLine("{0} * {0} = {1}", num1, Multiple(num1));

Console.WriteLine("5! = " + Fact(5)); //Recursion
Console.WriteLine("6! = " + Factorial(6));

Console.WriteLine("Log10(136) = " + Math.Log10(136));

#endregion

#region Enum
Console.WriteLine("\nENUM"); // Enumerator

Gender wordGender = Gender.Neutrum;
Gender word2Gender = (Gender)1; // cast

Console.WriteLine("word Gender: " + wordGender);
Console.WriteLine("word2 Gender: " + word2Gender);
if (wordGender == Gender.Neutrum)
{
	Console.WriteLine("word Gender: " + wordGender.ToString());
	Console.WriteLine("word Gender Id: " + (int)wordGender);
}

Sex personSex = Sex.Male;
Console.WriteLine("Sex: " + personSex.ToString());
Console.WriteLine("Sex: " + personSex.GetDescription());

Console.WriteLine("All Genders:");
foreach (Gender gender in Enum.GetValues(typeof(Gender)))
{
	Console.WriteLine("- {0}", gender.GetDescription());
}
#endregion

#region Classes
Console.WriteLine("\nCLASSES");

decimal xReal = 2, xImag = 3;
decimal yReal = 4, yImag = 5;
decimal zReal, zImag;

zReal = Add(xReal, yReal);
zImag = Add(xImag, yImag);

ComplexNumber xComplex = new ComplexNumber(2, 3);
ComplexNumber yComplex = new ComplexNumber(4, 5);
ComplexNumber zComplex = xComplex.Add(yComplex);


// System Class
DateTime currentDate = DateTime.Now;
Console.WriteLine("DateTime.Now() = {0}", currentDate);
Console.WriteLine("Date = {0} ", currentDate.ToString("dd.MM.yyyy"));
Console.WriteLine("Date = {0:dd.MM.yyyy} ", currentDate);
Console.WriteLine("Year = " + currentDate.Year);

// Custom Classes
// ComplexNumber
Console.WriteLine("");
Console.WriteLine(ComplexNumber.Format);
Console.WriteLine(ComplexNumber.GetDescription());

ComplexNumber complex0 = new ComplexNumber();
complex0.Real = 1;

ComplexNumber complex1 = new ComplexNumber(5, 3);
double r = complex1.Real;

ComplexNumber complex2 = new ComplexNumber
{
	Real = 6,
	Imag = 7
};

ComplexNumber complex3;
complex3 = new ComplexNumber()
{
	Real = 4,
	Imag = 2
};

MoreComplexNumber complex4 = new MoreComplexNumber(4, 2);
MoreComplexNumber complex = new MoreComplexNumber();

ComplexNumber summation = complex1.Add(complex2).Add(complex3);
//ComplexNumber summation2 = ComplexNumber.Add(ComplexNumber.Add(complex1, complex2), complex3);

ComplexNumber division = complex1.Divide(complex2);

Console.WriteLine("c0 = " + complex0);
Console.WriteLine("c1 = " + complex1);
Console.WriteLine("c2 = " + complex2.ToString());
Console.WriteLine("c3 = " + complex3.ToDiffString());
Console.WriteLine("c4 = " + complex4.ToDiffString());

Console.WriteLine("\nsummation = " + summation.ToDiffString());
Console.WriteLine("division = " + division.ToDiffString());
Console.WriteLine("minus = " + new ComplexNumber(2, -5).ToDiffString());
Console.WriteLine("real = " + new ComplexNumber(7, 0).ToDiffString());

Console.WriteLine("c1(modul) = " + complex1.Modul());
Console.WriteLine("c1 ^ 0 =" + complex1.Pow(0));
Console.WriteLine("c1 ^ 1 =" + complex1.Pow(1));
Console.WriteLine("c1 ^ 2 =" + complex1.Pow(2));
Console.WriteLine("c1 ^ 4 =" + complex1.Pow(2));
Console.WriteLine("c1 ^ (-2) =" + complex1.Pow(-2));

List<ComplexNumber> roots = complex1.Nroot(3);
Console.WriteLine("c1 ^ (1/3) = ");
foreach (var c in roots)
	Console.WriteLine(c);

// User
User user = new User()
{
	FirstName = "John",
	LastName = "Reacher",
	PersonSex = Sex.Male,
	BirthDate = DateTime.Parse("12/5/1987"),
	UserName = "Johnny",
	Email = "joe@gmail.com",
	Company = "Google",
	YearsOfService = 5,
	Sallary = 2000/*,
	HomeAddress = new Address()
	{
		City = "Banjaluka",
		Street = "Jevrejska"
	}*/
};

user.ResetPassword("1234abc!");

user.HomeAddress = new Address()
{
	City = "London",
	Street = "Baker Street"
};

Console.WriteLine("\nUSER: " + user);
Console.WriteLine("Year of Birth: " + user.BirthDate.Year);
Console.WriteLine("City: " + user.HomeAddress.City);

Square Square = new Square(4);
Console.WriteLine("Square(side:4), area = " + Square.CalcArea());

#endregion

#region InputConsole
Console.WriteLine("INPUT (console)");
string input = null;

while (input != "")
{
	Console.Write("\nInput number:");
	input = Console.ReadLine();
	bool inputValid = int.TryParse(input, out int inputNum);
	if (inputValid)
		Console.WriteLine("Number is valid. (Press Enter to Finish)\n");
	else
		Console.WriteLine("Number is not valid.(Press Enter to Finish)\n");
}
#endregion

#region InputFile
Console.WriteLine("INPUT (file)");
Console.Write("\nInput file path(Enter for no file, 'd' for default[ComplexIn.csv]): ");

string desktop_path = Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + "//";

string filePath = null;
string inputFilePath = Console.ReadLine();
if (inputFilePath == "d")
	inputFilePath = "ComplexIn.csv";
if (inputFilePath != "")
	filePath = desktop_path + inputFilePath;

string output_file = "ComplexOut.csv";
string line = null;
char separator = ',';

List<ComplexNumber> complexNumbers = new List<ComplexNumber>();

if (inputFilePath != "")
	using (StreamReader str_reader = new StreamReader(filePath))
	{
		str_reader.ReadLine(); // skips first line as it contains names of columns
		while ((line = str_reader.ReadLine()) != null)
		{
			string[] values = line.Split(separator);
			complexNumbers.Add(new ComplexNumber(Double.Parse(values[0]), Double.Parse(values[1])));
		}

		//output all objects to the file
		string output_path = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
		using (StreamWriter wr = new StreamWriter(desktop_path + output_file))
		{
			wr.WriteLine("Real,Imag");
			foreach (var complexNumber in complexNumbers)
				wr.WriteLine(complexNumber.ToCSV());
		}
	}
Console.WriteLine("Press Enter for Quit.");
Console.ReadKey();
// Don't copy code, all that is repeated should be in functions

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