/C-CHEAT-SCHEET

CSharp Cheat Sheet Template

Keyword Summary Sample Code Mentioned In
; Used to separate statements from each other. int i = 5; i++; Console.WriteLine(i); Script Execution
// Used for single-line comments float multiplier = 0.01f; // % to float (e.g. 24% = 0.24) Comments
Variable Initialization When a value is assigned to a variable for the first time int a = 5; Variables
dotnet new console -o project-name Used to make a new console script and you type it in your CMD ? Creat Project
Script Execution Order The order where code starts and ends. ? ?
Formatting Converts the value of objects to strings based on the formats specified and inserts them into another string. ? ?
Console.WriteLine Writes on to the console on a new Line Console.WriteLine("HelloWorld"); Hello World
Console.Write Write on the console on the same line Console.Write("HelloWorld"); Hello World
Multi-Line Comment Multi-Line Comment is to Comment out Big things in your code so the console cant read it This is how you write it */ Commet
XML Documentation Comment HTML- och XML-dokument innehåller data som omges av taggar, men där slutar likheten mellan de två språken. ? XML
Variable Variable are used to store data, Variable consist of type and name. int = x; Variables
Variable Declaration ? int=x; Variables
Variable Assignment Here I Assign the Variable to the number 5 int x = 5; Variables
Uninitialized Variable This will give you an error if you just write this. int = x; Console.WriteLine(x); Variables
= (Assignment Operator) This mean that I Assign two things or something to something. int = x; int x= 5; Variables
Scope ? ? ?
Variable Scope ? ? ?
int Interture is a Number int x = 5; BasicDataType
float This is a Fractional numbers float numberCool=0.004f; BasicDataType
double Same as int but prints out decimal Number double x= 0.004; BasicDataType
bool Bool Varibles print out true or false statements bool isWinning=True; BasicDataType
char Char print out only a singel character char euroSign = "€"; BasicDataType
string String can fit text. string name="Isak"; BasicDataType
byte ? ?
Implicit Casting Type casting is when you assign a value of one data type to another type. int myInt = 9; double myDouble = myInt; Casting
Explicit Casting Explicit casting must be done manually by placing the type in parentheses in front of the value: double myDouble = 9.78; int myInt = (int) myDouble; Casting
Type Conversion There is Conversion from String to Int And int to string and bool to string. int myInt= 5; nsole.WriteLine(Convert.ToString(myInt)); //OutPut: covert int to string. Conversion
Convert.ToInt32 Convert to Double to int. int myInt= 5; onsole.WriteLine(Convert.ToDouble(myInt)); Conversion
Operators Operators are functions represented by symbols int x = 5 + 5; // x = 10 Operators
Arithmetic Operators Arithmetic operators are used for mathematical operations Operators
+ Plus is just plus int d = x + x Operators
- Minus is just Minus int y = x -t; Operators
* Multiplictaion int x= y*u Operators
/ Divide int u=t/u Operators
% Modules Returns the division remainder x%y Operators
+= Plus to things. x += 3; x = x + 3; Operators
-= Minus to things x -= 3; x = x - 3; Operators
++ Increment Increases the value of a variable by 1: x++ Operators
-- Decrement Decreases the value of a variable by 1: x-- Operators
Post-Increment i++ Adds i Again after. Operators
Pre-Increment ++i Adds i Before i Operators
System.Math System.Math is a static class containing many useful functions for numbers. static means, it can not be instantiated, you can not write Math math = new Math(); int max = Math.Max(5, 3); Math
static Static means, it can not be instantiated. static void Main(){}
Math.Max Get the Max Value of two Number int max = Math.Max(5,4); Output: 5 Math
Math.Min Gets The Min value of two number int min = Math.Min(3,4); Output: 3 Math
Math.Sqrt Gets the SquareRoot of a Value double sqrt= Math.Sqrt(16); Output: 4 Math
Math.Abs returns a number that is allways positivt double abs= Math.Abs(-4.5); Output: 4.5 Math
Math.Round Returns Rounded number. Closest to the number. double round = Math.Round(12.6); Output: 13 Math
Math.Floor Returns Rounded number. But Round down. double floor = Math.Floor(12.6); Output: 12 Math
Math.Ceiling Returns Rounded number. But Round down. double ceil = Math.Ceiling(12.1); Math
Math.Clamp int Clamp(int value, int min, int max) returns the value made fit min and max double clamp = Math.Clamp(15, 0, 10); Math
Math.Pow double Pow(double value, double power) returns the value to the power of power. double pow = Math.Pow(2, 3); Math
string.Length Gets the strings lenght string txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; Console.WriteLine("The length of the txt string is: " + txt.Length); Output: The length of the txt string is: 26 String
string.ToUpper String to upper meens it will make your string to uppercases. string firstName="John"; string toUpper= firstName.ToUpper; Output= JOHN. String
string.+ This is just used for plus opperator string text= "what ever"+ "you say"; Console.WriteLine("what ever you say"); String
$"{}" Can put in varibles into what you want to print. We can combine strings using String-Interpolation. Put the $-operator before a string and variables between { and } Console.WriteLine($"You have this many eggs{egg Solution.}") String
string.[] This is used for stor string arrays or if you wnat to get a leter in the text string kings []= new kings [3]; string hello= "Hello" Console.Writeline(helloe[1]); Output: e Arrays String
string.IndexOf You can also find the index position of a specific character in a string, by using the IndexOf() method: string myString = "Hello";Console.WriteLine(myString.IndexOf("e")); // Outputs "1" String
string.SubString(int) Another useful method is Substring(), which extracts the characters from a string, starting from the specified character position/index, and returns a new string. This method is often used together with IndexOf() to get the specific character position: string name= "John Daniel"; int charPos = name.IndexOf(D); string lastName= name.SubString(charPos) Console.WriteLine(lastName); String
string.Substring(int, int) ? ? ?
string.Replace Returns a new string in which all occurrences of a specified Unicode character or String in the current string are replaced with another specified Unicode character or String. public string Replace (char oldChar, char newChar); String
immutable Mutable and immutable are English words that mean "can change" and "cannot change" respectively. The meaning of these words is the same in C# programming language; that means the mutable types are those whose data members can be changed after the instance is created but Immutable types are those whose data members can not be changed after the instance is created. class MyClass {private readonly string myStr; public MyClass(string str) { myStr = str; } public string GetStr { get { return myStr; } } Immutable
Logical Operators Logical operators are used to determine the logic between variables or values: ? Operators
! Reverse the result, returns false if the result is true. !(x < 5 && x < 10) Operators
&& Returns true if both statements are true x < 5 && x < 10 Operators
|| Returns true if one of the statements is true x < 5 || x < 4 Operators
Comparison Operators Comparison operators are used to compare two values: ? Operators
> Greater than x>y Operators
== Equal to x==y Operators
!= Not equal x!=y Operators
>= Greater than or equal to x>=y Operators
<= Smaller than or equal to x<=y Operators
if Use if to specify a block of code to be executed, if a specified condition is true if(condition){ // block of code to be executed if the condition is True} Operators
else Use the else statement to specify a block of code to be executed if the condition is False. else {// block of code to be executed if the condition is False} Operators
else if Use the else if statement to specify a new condition if the first condition is False. else if(condition2){// block of code to be executed if the condition1 is false and condition2 is True} Operators
? : C# includes a decision-making operator ?: which is called the conditional operator or ternary operator. It is the short form of the if else conditions. condition ? statement 1 : statement 2 Operators
Flow Control Statements Like in any programming language, C# provides statements that can change the sequence of program execution. If you have seen or worked with flow charts, you can easily visualize that it's very frequent when we require decision boxes that indicate how the program flow can change based on condition(s). So, let's see how we can use different C# statements to control and change the flow of program execution. ? Flow Control
System.Random Represents a pseudo-random number generator, which is an algorithm that produces a sequence of numbers that meet certain statistical requirements for randomness. public class Random Random
pseudo-random The numbers are pseudo-random: they are using complex mathematical operations to make them appear random* They are guaranteed to be evenly ditributed across all numbers Random
seed That‘s a feature: we can reproduce the same random numbers if we know the seed. Random random = new Random(23746); Random
Random.Next(int, int) Returns a random integer that is within a specified range. public virtual int Next (int minValue, int maxValue); Random
Random.Next() int Next() gets a random integer between 0 and int.MaxValue (1.2 bln).Returns a non-negative random integer. int number = random.Next(); RandomMicrosoft RandomGithub
Random.NextDouble() Returns a random floating-point number that is greater than or equal to 0.0, and less than 1.0. Double NextDouble() Receive a new randomNumber between 0 (inclusive) and 1 (exclusive), so anything between 0.000000 and 0.9999999 double number = random.NextDouble(); RandomMicrosoft RandomGithub
while The while loop loops through a block of code as long as a specified condition is True: while(condition){// code block to be executed} While
bool-expression A Boolean expression is a C# expression that returns a Boolean value: True or False. You can use a comparison operator, such as the greater than (>) operator to find out if an expression (or a variable) is true: int x = 10; int y = 9; Console.WriteLine(x > y); Bool
do..while The do/while loop is a variant of the while loop. This loop will execute the code block once, before checking if the condition is true, then it will repeat the loop as long as the condition is true. do {// code block to be executed}while (condition); While
for When you know exactly how many times you want to loop through a block of code, use the for loop instead of a while loop: for (statement 1; statement 2; statement 3) {// code block to be executed} ForLoop
iteration statement Runs once every iteration. 'for (int i = 0; i < 3; i++){ Console.Write(i); }' iteration statement
loop body The body containing the code that the loop runs. ? iteration statement
loop code that runs multiple times. ? iteration statement
execution Running a line of code. ? ?
execution jump Jumps to the beginning or end of a loop. ? ?
break Stops the loop and skips the remaining body of the loop. ? ?
continue Starts a new iteration of the loop. ? ?
Array A array of variables. ? ?
int[] A array of ints int[] array = new int[5]; Int Arrays
Array Initialization Requires a type and a lenght. string[5] stringArray" creates a string array of lenght 5. Array Initialization
Array Access for Assignment To set values in the array. stringArray[2] = "Index2" ?
Array Access for Reading Gets the values of specified index in a array. stringArray[2]; returns the value at index 2. ?
Array.Resize Resizes the array. Actually just creates a new one with the new length and copies over the values. public static void Resize<T> (ref T[]? array, int newSize); Array Resize
Array.Length Returns the length of the array. public int Length { get; } Array.Length
foreach For loop that goes through each element in a list or array. foreach(string s in stringArray) runs 5, and each new iteration has string s set to the next value in the array. (In this case) ?
2D-Array A array which contains arrays. int[,] array2D = new int[,] { { 1, 2 }, { 3, 4 }, { 5, 6 }, { 7, 8 } }; 2D-Array
2D-Array Initialization string[,] 2dStringArray = new string[9,4]; string[,] 2dStringArray = new string[9,4]; ?
2D-Array Access for Assignment 2dStringArray[5][2] = "Hej"; 2dStringArray[5][2] = "Hej"; ?
2D-Array Access for Reading 2dStringArray[5][2] 2dStringArray[5][2] ?
Jagged Arrays Like 2d strings but with varying secondary array lengths. int[][] jaggedArray = new int[3][]; Jagged Arrays
Method A chunk of code that can be called and can return a value. `` ?
void Specifies that the method does not return anything. `` ?
Return Type What the method returns. void, int, string, List, etc `` ?
() Holds arguments for a method. static string SayHello(string name) ?
Parameter Other word for method arguments. `` ?
Argument Is a variable that the method wants passed to itself. `` ?
Parameter ? `` Parameter
Parameter-List A method can have multiple paratmeters. ? Parameter-List
Named Arguments You can use names for the arguments when calling the method, allowing you to have them in different orders. static void t(int a, int b) t(b: 5, a:3); ?
Optional Arguments You can make a argument have a default value which lets the caller not have to use all arguments. int integer = 5 ?
Default Value A defualt value for a argument. static void temp(int integer = 5) ?
return Returns the value specified. Needs to match the type as told in the method initializer. public ref Person GetContactInformation(string fname, string lname){// ...method implementation... return ref p;} Return
Code Paths Each code path in a method needs to return a value. If a if statements leads to a code path that does not return anything, we get a error. `` ?
Method Overloading Lets you create multiple methods with the same name. They do need to have a different amout of arguments, or arguments of different types. static void temp(int integer) and static void temp(string string) ?
Object-Oriented Programming Means we use functions that require data as input, and returns data. Then we have data that only stores information and nothing else. `` ?
Data Stores infomation `` ?
Function Uses data to do stuffs. `` ?
Structured Programming Divide program into functions and data. `` ?
Objects Contains both functions and data. `` ?
Instance Method A method that becomes part of its class. `` ?
Class A colletion of functions and objects that can be called and initalized. class TestClass{ // Methods, properties, fields, events, delegates // and nested classes go here. } Class
Type A class is a type, like a template for objects. `` ?
class ? `` ?
new Create a new instance of a class. MyClass test = new MyClass(); Random rnd = new Random(); ?
Class Member Parts of the class. Can be methods, fields, `` ?
Class Instance The current instance of the class. `` ?
Garbage Collector C# built in garbage collector. Will clean up old things that are no longer in use, like class instances. Can be manually started with: GC.Collect(); ?
null No value, or no instance. `` ?
Invoke Run a member method inside a class from outside of the class. `` ?
Field A variable that belongs the the current class instance. public string instanceName; ?
Static Class Member When a class memeber is static it is part of the class type, which means it is called by className.membername. `` ?
Static Class Requires all memebers to be static. And you will no longer use "new" to create a instance of the class. `` ?
Global Access If something can be accessed everywhere. `` ?
Constructor Code that runs when a class is initialized. if you have a class MyClass, then adding public MyClass() { } is the constructor. ?
Initial Class Values Specified in the constructor. `` ?
Parameterless If no parameters are specified, the class actually contains a secret hidden parameterLess constructor. `` ?
Default Contructor A secret hidden parameterless constructor. `` ?
Finalizer A code chunk which runs when the class is destoryed by the GC. ClassName() { finalizer-body } ?
Object Destruction Done by the garbage collector, GC. Can be triggered manually. `` ?
GC.Collect Method to start the garbage collector. GC.Collect(); ?
Encapsulation The art of encapsulating data and functions into a single unit, a class. `` ?
Access Modifier Specifies who can and can not access this object. `` ?
private Only the owning class can use it. Use this as much as possible, has many benefits. `` ?
protected All inheriting classes and the owner can access. Only use when inheriting classes requires it. `` ?
public Every class can access it. Only use for things that needs to be available everywhere. `` ?
internal Every class inside the same project can access it. `` ?
Class Member Access Can use the same access modifiers. `` ?
Inheritance The way of using base classes with basic functions and then more speficied classes inheriting them to do advanced things. Like characters in games. A basic class controls healt and movement of a entity. A inheriting class might add functions like a dash ability, or similar. Without the need to repeat the code for movement and health. ?
Property A method disguised as a field. They can be used to set values of private variables, and get their values too. Can also contain logic to modify the input value to fit the class. `` ?
Getter Method Gets the value of the private var, and returns that to the caller. `` ?
Setter Method Runs when the caller provides a variable, and depending on the logic written, sets the value of the private var. `` ?
Validation You can use set to validate that the set variable you want to set is valid and wont break the program. `` ?
Processing You can also use set to process the provided data into something else. `` ?
get is the getter method. Can use with only get; to make the code shorter. `` ?
set is the setter method. Can use with only set; to make the code shorter. `` ?
Expression Body Syntax Even more shortening of code. get => this.value; set => this.value = newValue; ?
Auto Property Uses get; set; When used it will create a hidden field that you cannot access in any other way. get; set; ?
Read-Only Property Auto properties can only have a get, making it read only. But you can still assign a value in the constructor. `` ?
Auto Property ? `` ?
base-Class The first class in the inheritance tree, usually holds most basic functions than all childs will use/override. `` ?
Inherit From How to specify what to inherit from public class MyClass : ParentClass ?
Derived Class Other word for child class. `` ?
Child Class Other word for Drived class. `` ?
Parent Class Other word for the base class. `` ?
sealed Keyword will prevent other classes from inheriting from this class. public sealed class MyClass ?
Polymorphism Since each child class also has the members of the parent the child can act as the parent. `` ?
as You can cast a parent class as a child, but if you then use as to set the parent as a child, it has to be the correct child, otherwise you get a null. `` ?
virtual The virtual keyword makes a class member overrideable by child classes. `` ?
override The override keyword lets a claass member override a parent class with the same name. `` ?
base References the base class. Can be used when overriding to call the base class. base.Myclass(); ?
Abstraction The art of having a base class that doesn't do anything on its own. It needs a child to have a purpose or use, and can not be called on it's own. `` ?
abstract he keyword makes a class abstract, which prevents it from being initialized, even when it has a constructor. To instantiate the class you need to instantiate a child of it. `` ?
Implementation ? `` ?
Composition Instead of inheritance. Sometimes a object has something, but it doesn't belong with other things using that same object. A bird and a plane both have wings, but a bird doesn't need to have the possibility to be driven or enterd. `` ?
Composition over Inheritance ? `` ?
Escaped character In a string if you want to use the " you can use a backslash before to prevent the string from ending. string s = "Hej mitt namn är "Johannes""; ?
Serialization / Serializable To save something, or to convert data to text, opposite of parse. ? ?