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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**Also take a look into others packages:
Open source (MIT or cFOSS) authored .Net libraries (@Infopedia.io personal blog post)
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|---|---|---|
| 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 |
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.
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 digitsdouble (+- 5.0 E−324 to +- 1.7976931348623157 E+308) [default: 0] Precision: ~15-17 digitsdecimal / Decimal (+- 1.0 E-28 to +- 7.9228 E28) [default: 0] Precision: 28-29 digitschar / Char [default: '']string / String [default: null, nullable]var // can be any type*/
#endregion
#region Naming Conventions
/*local variables - nonCapitalLetter, camelCaseClass, Function(Method - in a class) and Property name - CapitalLetter, PascalCaseDO 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)boolisAdmin;intcounter;doublesum;decimalnumber;charcharacter;stringname;// Assignment of variableisAdmin=true;counter=5;sum=3.14;number=18.65m;character='a';name="Ben Benito";Console.WriteLine("c"+counter);// Declaration and AssignmentboolisActive=true;// Nullable (can take all values of its underlying value type and an additional null value)bool?isEnded=null;stringcity=null;// String is null (and therefore nullable) by default, so there's no need for this notation)// CastintinputAmount=126;decimalsecondAmount=inputAmount;// implicit castintthirdAmount=(int)secondAmount;// explicit caststringstrNum="1234";intoutputNum=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 interpolationConsole.WriteLine("City Name: "+city);// Old way to concatenate stringsConsole.WriteLine("City Name: {0}",city);Console.WriteLine($"City Name: {city}");// Newest way, from C# 6 versionConsole.WriteLine();
#endregion
#region Operators
// Arithmetic Operators// = + - * / %intx=10,y=6;// Declaration and assignment of multiple variables of the same type at onceintresult=x+y;Console.WriteLine("OPERATORS");Console.WriteLine("a + b = "+x+" + "+y+" = "+result);Console.WriteLine("a + b = {0} + {1} = {2}",x,y,result);Console.WriteLine($"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 incrementingConsole.WriteLine("x= "+x);Console.WriteLine("r = ++x = "+++x);// output is the value of x AFTER incrementingConsole.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, caseboolprint=true;if(print)Console.WriteLine("true - ");print=false;if(print)Console.WriteLine("false - no output");if(!print)Console.WriteLine("not false = true - output");intage=20;if(age>18)Console.WriteLine("Adult");elseConsole.WriteLine("Minor");intvalue=23;// value range 0-29stringclause="Value is from-to: ";if(value>=0&&value<10)Console.WriteLine(clause+"0-9");elseif(value>=10&&value<20)Console.WriteLine(clause+"10-19");elseif(value>=20&&value<30)Console.WriteLine(clause+"20-29");elseConsole.WriteLine(clause+"30+");intmod=value%3;if(mod==1)Console.WriteLine("Remainder 1");elseif(mod==2)Console.WriteLine("Remainder 2");elseConsole.WriteLine("Divisible with 3");switch(mod){case1:Console.WriteLine("Remainder 1");break;case2: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 resultConsole.WriteLine("Year = "+(year??2017));// returns 2017, as year == nullstringyearType=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-catchConsole.Write("For loop: ");for(inti=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 fulfilledintk=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=newdouble[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(inti=0;i<5;i++){Console.Write(fiveDayPrices[i]+" ");}Console.Write("\nFive day prices backwards: ");for(inti=fiveDayPrices.Length-1;i>=0;i--){Console.Write(fiveDayPrices[i]+" ");}Console.Write("\nForeach: ");foreach(varelementinfiveDayPrices){Console.Write(element+" ");}Console.WriteLine("");Console.WriteLine("Matrix");// Multidimensional arrays// Two-dimensional array. int[,]matrix=newint[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(inti=0;i<3;i++)for(intj=0;j<3;j++)Console.Write(matrix[i,j]+" ");Console.WriteLine();int[,]matrixB=newint[3,3];// fixed size;for(inti=0;i<3;i++){for(intj=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=newstring[3,2]{{"one","two"},{"three","four"},{"five","six"}};// Three-dimensional array. int[,,]array3D=newint[,,]{{{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=newint[3][];for(inti=0;i<3;i++){jaggedArray[i]=newint[(i+1)];for(intj=0;j<(i+1);j++){jaggedArray[i]=newint[(i+1)];jaggedArray[i][j]=(i*3)+j+1;Console.Write(jaggedArray[i][j]+" ");if((j+1)%(i+1)==0)Console.WriteLine("");}}// ListList<string>words=newList<string>{"one","two","three",};words.Add("four");words.Add("five");words.Remove("three");Console.WriteLine("");foreach(varwordinwords)Console.Write(word+" ");Console.WriteLine("\n"+words[1]);Console.WriteLine(words.ElementAt(1));List<char>letters=newList<char>(){'a','b','c'};foreach(varletterinletters){Console.Write(letter+" ");}// DictionaryDictionary<String,int>accounts=newDictionary<String,int>{{"Cash",110},{"Receivable",120},{"Supplies",130},};accounts.Add("Insurance",150);accounts.TryGetValue("Supplies",outintaccount);Console.Write("\nSupplies account: "+account);List<string>sentences=newList<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, ContainsList<string>ingEndSentences2=sentences.Where(a =>a.EndsWith("ing")).ToList();// EndsWith, ContainsConsole.WriteLine("\nING:");foreach(varsentenceiningEndSentences2){Console.WriteLine(sentence);}List<string>ingEndSentences3=newList<string>();foreach(varsentenceinsentences){if(sentence.EndsWith("ing")){ingEndSentences3.Add(sentence);}}
#endregion
#region Parsing and Exceptions
Console.WriteLine("\n\nPARSING AND EXCEPTIONS");stringcustomNumStr="324erer";intcustomNum;varvalidNum=int.TryParse(customNumStr,outcustomNum);if(validNum)Console.WriteLine(customNum);elseConsole.WriteLine("Parse Error");try{customNum=Int32.Parse(customNumStr);}catch(Exceptionex){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 instantiationPrintText("To be printed.");PrintText("End.");decimalnum1=12.3m;decimalnum2=2.5m;intnum3=3;decimalquotient=Divide(num1,num2);// num1, num2 are Arguments - values on function callConsole.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));//RecursionConsole.WriteLine("6! = "+Factorial(6));Console.WriteLine("Log10(136) = "+Math.Log10(136));
#endregion
#region Enum
Console.WriteLine("\nENUM");// EnumeratorGenderwordGender=Gender.Neutrum;Genderword2Gender=(Gender)1;// castConsole.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);}SexpersonSex=Sex.Male;Console.WriteLine("Sex: "+personSex.ToString());Console.WriteLine("Sex: "+personSex.GetDescription());Console.WriteLine("All Genders:");foreach(GendergenderinEnum.GetValues(typeof(Gender))){Console.WriteLine("- {0}",gender.GetDescription());}
#endregion
#region Classes
Console.WriteLine("\nCLASSES");decimalxReal=2,xImag=3;decimalyReal=4,yImag=5;decimalzReal,zImag;zReal=Add(xReal,yReal);zImag=Add(xImag,yImag);ComplexNumberxComplex=newComplexNumber(2,3);ComplexNumberyComplex=newComplexNumber(4,5);ComplexNumberzComplex=xComplex.Add(yComplex);// System ClassDateTimecurrentDate=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// ComplexNumberConsole.WriteLine("");Console.WriteLine(ComplexNumber.Format);Console.WriteLine(ComplexNumber.GetDescription());ComplexNumbercomplex0=newComplexNumber();complex0.Real=1;ComplexNumbercomplex1=newComplexNumber(5,3);doubler=complex1.Real;ComplexNumbercomplex2=newComplexNumber{Real=6,Imag=7};ComplexNumbercomplex3;complex3=newComplexNumber(){Real=4,Imag=2};MoreComplexNumbercomplex4=newMoreComplexNumber(4,2);MoreComplexNumbercomplex=newMoreComplexNumber();ComplexNumbersummation=complex1.Add(complex2).Add(complex3);//ComplexNumber summation2 = ComplexNumber.Add(ComplexNumber.Add(complex1, complex2), complex3);ComplexNumberdivision=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 = "+newComplexNumber(2,-5).ToDiffString());Console.WriteLine("real = "+newComplexNumber(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(varcinroots)Console.WriteLine(c);// UserUseruser=newUser(){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=newAddress(){City="London",Street="Baker Street"};Console.WriteLine("\nUSER: "+user);Console.WriteLine("Year of Birth: "+user.BirthDate.Year);Console.WriteLine("City: "+user.HomeAddress.City);SquareSquare=newSquare(4);Console.WriteLine("Square(side:4), area = "+Square.CalcArea());
#endregion
#region InputConsole
Console.WriteLine("INPUT (console)");stringinput=null;while(input!=""){Console.Write("\nInput number:");input=Console.ReadLine();boolinputValid=int.TryParse(input,outintinputNum);if(inputValid)Console.WriteLine("Number is valid. (Press Enter to Finish)\n");elseConsole.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]): ");stringdesktop_path=Environment.GetFolderPath(Environment.SpecialFolder.Desktop)+"//";stringfilePath=null;stringinputFilePath=Console.ReadLine();if(inputFilePath=="d")inputFilePath="ComplexIn.csv";if(inputFilePath!="")filePath=desktop_path+inputFilePath;stringoutput_file="ComplexOut.csv";stringline=null;charseparator=',';List<ComplexNumber>complexNumbers=newList<ComplexNumber>();if(inputFilePath!="")using(StreamReaderstr_reader=newStreamReader(filePath)){str_reader.ReadLine();// skips first line as it contains names of columnswhile((line=str_reader.ReadLine())!=null){string[]values=line.Split(separator);complexNumbers.Add(newComplexNumber(Double.Parse(values[0]),Double.Parse(values[1])));}//output all objects to the filestringoutput_path=Environment.GetFolderPath(Environment.SpecialFolder.Desktop);using(StreamWriterwr=newStreamWriter(desktop_path+output_file)){wr.WriteLine("Real,Imag");foreach(varcomplexNumberincomplexNumbers)wr.WriteLine(complexNumber.ToCSV());}}Console.WriteLine("Press Enter for Quit.");Console.ReadKey();// Don't copy code, all that is repeated should be in functions