C# Cheatsheet.zip

# C# Cheatsheet - [PDF Download Cheatsheet](https://1drv.ms/b/s!Ai0GNI50Q5GAgdQzF5Ynuo_6GZmofg) <div align="center"> <img src="https://i2.wp.com/programmingwithmosh.com/wp-content/uploads/2015/10/Cover.jpg" width=100%/> </div> <br> <br> <br> # Index<br> [Comments](#Comments)<br> [Scopes](#Scopes)<br> [Functions](#Functions)<br> [Params Keyword](#Params-Keyword)<br> [DataTypes ](#DataTypes )<br> [Operators](#Operators)<br> [Convert Data Types](#Convert-Data-Types)<br> [Define Variables](#Define-Variables)<br> [Initialise Varaiable](#Initialise-Varaiable)<br> [Constants](#Constants)<br> [Casting User input](#Casting-User-input)<br> [Classes](#Classes)<br> [Properties](#Properties)<br> [Constructor](#Constructor)<br> [Method Overloading](#Method-Overloading)<br> [Class Visability](#Class-Visability)<br> [Inheritance](#Inheritance)<br> [Virtual and Override](#Virtual-and-Override)<br> [Base](#Base)<br> [Abstract Class](#Abstract-Class)<br> [Abstract methods](#Abstract-methods)<br> [Interfaces](#Interfaces)<br> [Partial Classes](#Partial-Classes)<br> [Collections](#Collections)<br> [Arrays](#Arrays)<br> [ForLoop](#ForLoop)<br> [ForEach](#ForEach)<br> [Lists](#Lists)<br> [Dictionaries](#Dictionaries)<br> [Strings](#Strings)<br> [Common String Methods](#Common-String-Methods)<br> [Structs or Structures](#Structs-or-Structures)<br> [Enums](#Enums)<br> [Read File](#Read-File)<br> [Write File](#Write-File)<br> [Create a File](#Create-File)<br> ## Comments ```c# // My comments about the class name could go here... // My comments about the class name could go here... // Add as many lines as you would like // ...Seriously! /* My comments about the class name could go here... Add as many lines of comments as you want ...and use indentation, if you want to! */ ``` ## Commented Tasks highlighter ```c# //TODO: Change "world" to "universe" //HACK: Don't try this at home.... //NOTE: Don't try this at home.... //UNDONE: Don't try this at home.... ``` <br> [back to top](#Index)<br> <br> # Scopes Block/Function Scoped Class Scoped ```c# using System; namespace VariableScope { class Program { private static string helloClass = "Hello, class!"; static void Main(string[] args) { string helloLocal = "Hello, local!"; Console.WriteLine(helloLocal); // Hello local Console.WriteLine(Program.helloClass); // Hello Class DoStuff(); } static void DoStuff() { Console.WriteLine("A message from DoStuff: " + Program.helloClass); // Hello Class } } } ``` <br> [back to top](#Index)<br> <br> # Functions ## Syntax ```c# <visibility> <return type> <name>(<parameters>) { <function code> } ``` ```If you don't define any, then the function will be private``` ```void``` means it returns nothing. ### Example ```c# public int AddNumbers(int number1, int number2) { int result = number1 + number2; return result; } ``` ## Params Keyword We can create a function and pass parameters like this ```c# static void GreetPersons(string[] names) { } ``` However, calling it would be a bit clumsy. In the shortest form, it would look like this: ```c# GreetPersons(new string[] { "John", "Jane", "Tarzan" }); ``` By Adding the keyword params we can call it like this ```c# static void GreetPersons(params string[] names) { } ``` And call it like this, ```c# GreetPersons("John", "Jane", "Tarzan"); ``` Another advantage of using the params approach, is that you are allowed to pass ```zero parameters``` to it as well. <br> [back to top](#Index)<br> <br> ## DataTypes | Type | Description |Examples | | ------------- |:-------------:| -----:| | `int ` | Integer (whole numbers) | 103, 12, 5168| | `double` | 64 bit floating-point number | 3.14, 3.4e38| | `Float` | Floating-point number | 3.14, 3.4e38 | | `Decimal` | Decimal number (higher precision) | 1037.196543 | | `Bool` | Boolean | true, False| | `String` | String | "Hello World" | | `byte` | 8-bit unsigned integer | 0 to 255 | | `char` | 16-bit Unicode character | "A" | | `long` | 64-bit signed integer type | -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 | <br> [back to top](#Index)<br> <br> ## Operators | Operator | Description |Examples | | ------------- |:-------------:| -----:| | `=` | Assigns a value to a variable.| i=6 | `+` | Adds a value or variable. | i=5+5 | | `-` | Subtracts a value or variable. | i=5-5 | | `*` | Multiplies a value or variable. | i=5*5 | `/` | Divides a value or variable.| i=5/5 | `+=` | Increments a variable. | i += 1| | `-=` | Decrements a variable. | i -= 1 | | `==` | Equality. Returns true if values are equal. | if (i==10) | | `!=` |Inequality. Returns true if values are not equal. | if (i!=10) | `<` | Less Than | if (i<10) | `<=` | Greater Than | if (i>10)| | `>=` | Less Than or Equal to | if (i<=10) | | `+` | Adding strings (concatenation). | "Hello " + "World" | | `.` | Dot. Separate objects and methods. | DateTime.Hour | `()` |Parenthesis. Groups values. | (i+5) | `()` | Parenthesis. Passes parameters. | x=Add(i,5) | `[]` | Brackets. Accesses values in arrays or collections. | name[3] | `!` | Not. Reverses true or false. | if (!ready)| | `&&` | Logical AND. | if (ready && clear) | | `||` | Logical OR. | if (ready || clear) | <br> [back to top](#Index)<br> <br> ## Convert Data Types | Method | Description |Examples | | ------------- |:-------------:| -----:| |AsInt(),<br> IsInt() | Converts a string to an integer. | ``` if (myString.IsInt())```<br> ```{myInt=myString.AsInt();```| |AsFloat(), IsFloat()| Converts a string to a floating-point number.|```if (myString.IsFloat())```<br>```{myFloat=myString.AsFloat();}```| |AsDecimal(), IsDecimal()| Converts a string to a decimal number..|```if (myString.IsDecimal())```<br>```{myDec=myString.AsDecimal();}```| |AsDateTime(), IsDateTime()|Converts a string to an ASP.NET DateTime type.| ```myString="10/10/2012";```<br>``` myDate=myString.AsDateTime();```| |AsBool(),<br> IsBool()|Converts a string to a Boolean..| ```myString="True";```<br> ```myBool=myString.AsBool();```| |ToString()|Converts any data type to a string.| ```myInt=1234;```<br> ```myString=myInt.ToString();```| <br> [back to top](#Index)<br> <br> ## Define Variables int i, j, k; char c, ch; float f, salary; double d; | Type | Name | | ------------- |:-------------:| |```int```|i, j, k;| |```char```|c, ch;| |```float```|f, salary;| |```double```|d;| ## Initialise Varaiable ```c# variable_name = value; ``` You can also initialize a varaible at the same time you define it. ```c# int d = 3, f = 5; /* initializing d and f. */ byte z = 22; /* initializes z. */ double pi = 3.14159; /* declares an approximation of pi. */ char x = 'x'; /* the variable x has the value 'x'. */ ``` ## Constants ```c# // const <data_type> <constant_name> = value; const double pi = 3.14159; ``` <br> [back to top](#Index)<br> <br> ## Casting User input ```c# int num; num = Convert.ToInt32(Console.ReadLine()); ``` ## ? == Nullable Types C# provides a special data types, the nullable types, to which you can assign normal range of values as well as null values. ```c# // < data_type> ? <variable_name> = null; int? num1 = null; ``` <br> [back to top](#Index)<br> <br> # Classes * A Class is a group of related methods and variables. * On this object, you use the defined methods and variables. * You can create as many instances of your class as you want ```c# using System; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { // Declare a variable of type Car Car car; // Creates an new instance car =