Type tests

GetType() returns type reference of any var/type

GetType().IsAbstract:

IsArray:

myArr.GetType().IsArray : returns true

IsClass

IsEnum

IsInterface

IsPointer

IsPrimitive (one of the predefined primitive data types),

IsPublic

IsSealed

IsValueType: true if struct/enum (not verified)

typeof(obj)

Type t = typeof(MyClass);
if (typeof(obj)==Type.GetType(DateTime)) // it is DateTime

is : check if object is compatible with given type (ie can be cast)

if (obj is Class1) { a=(Class1)obj; }...

Expression (ternary operator)

x ? trueExpr : falseExpr ex: return x?3:77;

Constants

const float pi = 3.1415927f;

readonly var=x;

public static readonly myVar=7;

Similar to const but it can be changed in constructor.

public readonly myTime=DateTime.Now.Ticks;

Enum

default: uses int

enum Color {red,green,blue=5, purple= blue+24 }
Color a = Color.red;

Another Type: not using int:

enum Color : sbyte { ... }

Casting:

int i = (int)Color.red;
Color c = (Color)1;         // green

enum value as string outputs the string value, not int value. enum2str is necessary!:

WriteLine(Color.red); // output: ""red""
WriteLine(Color.red.ToString(""d"")); // output: ""0"" in string

.Parse(typeof(<enumType>),""string"")

parses the string and converts to appropriate enum value. Color currentColor =(Color)Enum.Parse(typeof(Color), ""blue"");

.GetValues(typeof(<enumType>)) : returns array of enums

Array arr = Enum.GetValues(typeof(Color)); // {""red"",""green"",""blue""}

[Flags]: attribute that sets this as a bit-combined flag

[Flags]
enum FONTF : byte { BOLD=1,ITALIC=2,UNDERLINE=4, SUPER=8, SUB=16}
FONTF myFont = FONTF.BOLD | FONTF.SUPER;
WriteLine (myFont); // output: ""BOLD, SUPER""
WriteLine (myFont.ToString(""d"")) ; // output: ""9""

Array

int[] a = new int[10];

Once array's size has been set, it cannot be changed.

initializing::

int[] a = new int[] {1, 2, 3}; // long version int[] a = {1, 2, 3}; // short-version

Dynamically creating array:

int arraySize=10;
string[] arr =new string[arraySize];

Multidimension:

int[,] a2 = new int[10, 5]; // multidim array
int[,,] a3 = new int[10, 5, 2];

jagged array:

int[][] a = new int[3][];
a[0] = new int[10];
a[1] = new int[5];
a[2] = new int[20];

.Length : get size of array

Array.Sort(myArray); // sorts ""myArray""

Array.CopyTo(destArray, destArrayIndexToInsert)

copies all elements in this array to the destArray starting at dest's index n.

Struct

Struct is similar to class and can have methods as well. However, struct exists in stack and class exists in heap. There is no need for new() in struct because it can exist in stack. However, class requires new().