C# Cheat Sheet...

C# Cheat Sheet

    Data Types

     Primitive   Size            Example

     String      2 bytes/char    s = "reference";
     bool                        b = true;
     char        2 bytes         ch = 'a';
     byte        1 byte          b = 0x78;
     short       2 bytes         val = 70;
     int         4 bytes         val = 700;
     long        8 bytes         val = 70;
     float       4 bytes         val = 70.0F;
     double      8 bytes         val = 70.0D;
     decimal     16 bytes        val = 70.0M;

    Arrays

    2.1 Declaration

    //Initiliazed using a list defined with curly braces
    int[] nameArray = {100, 101, 102};

    //Define an empty array
    int[] nameArray = new int[3]; // 3 rows and 2 columns

    //To access a specific item in the array
    int[] nameArray = new int[10];
    int firstNumber = nameArray[0];
    nameArray[1] = 20;

    //Multidimensional arrays
    int [,] matrix = new int [2,2]
    matrix[0,0] = 1;
    matrix[0,1] = 2;
    matrix[1,0] = 3;
    matrix[1,1] = 4;

    int[,] predefinedMatrix = new int[2,2] { { 1, 2 }, { 3, 4 } };

    2.2 Array Operations

    //Sort ascending
    Array.Sort(nameArray);

    //Sort begins at element 6 and sorts 20 elements
    Array.Sort(nameArray,6,20);

    //Use 1 array as a key & sort 2 arrays
    string[] values = {"Juan", "Victor", "Elena"};
    string[] keys = {"Jimenez", "Martin", "Ortiz"};
    Array.Sort(keys, values);

    //Clear elements in array (array, first element, # elements)
    Array.Clear(nameArray, 0, nameArray.Length);

    //Copy elements from one array to another
    Array.Copy(scr, target, numOfElements);

    String Operations

     //To concatenate between strings, use the plus operator:
     string firstName = "Erin";
     string lastName = "Roger";
     string fullName = firstName + " " + lastName;

     //To add one string to another, use the += operator:
     string secondLastName = "Green";
     string fullName += secondLastName;

     //ToString function
     //It converts an object to its string representation so that it is suitable for display
     Object.ToString();

     //String formatting
     //Each additional argument to the function can be referred to in the string using the brackets operator with the index number.
     String.Format(String format, Object arg0);
      format - A composite format string that includes one or more format items
      arg0 - The first or only object to format

     //Substring
     //Returns a part of the string, beginning from the index specified as the argument. Substring also accepts a maximum length for the substring
     String.Substring(beginAt);
     String.Substring(beginAt, maximum);

     //Replace
     string newStr = oldStr.Replace("old","new");

     //IndexOf
     //Finds the first ocurrence of a string in a larger string
     //Returns -1 if the string is not found
     String.IndexOf(val, start, num)
     val - string to search for
     start - where to begin in string

     //LastIndexOf
     //Search from end of string

     //Split
     //Split is used to break delimited string into substrings
     String.Split(Char[]);

     //ToCharArray
     //Places selected characteres in a string in a char array
     String str = "AaBbCcDd";
     //create array of 8 vowels
     var chars = str.ToCharArray();
     //create array of 'B' and 'C'
     var chars = str.ToCharArray(2,2);

    System.Text.StringBuilder

     4.1 Constructor

     StringBuilder sb = new StringBuilder();
     StringBuilder sb = new StringBuilder(myString);
     StringBuilder sb = new StringBuilder(myString, capacity);

     myString - Initial value of StringBuilder object
     capacity - Initial size of buffer

    DateTime

     5.1 DateTime Constructor

     DateTime(year, month, day)
     DateTime(year, month, day, hour, minute, second)

     DateTime newYear = DateTime.Parse("1/1/2018"):
     DateTime currentDate = DateTime.Now;
     DateTime nextYear = DateTime.AddYears(1);

    TimeSpan

     6.1 TimeSpan Constructor

     TimpeSpan(hour, minute, sec)

     TimeSpan timeS = new TimeSpan(10, 14, 50);
     TimeSpan timeS_Hours = TimeSpan.FromDays(3640);

    Formatting Values

     Format item syntax: {index[,alignment][:format string]}
     index - Specifies element in list of values to which format is applied
     aligment - Indicates minimun width (in characters) to display value
     format string - Contains the code which specififes the format of the displayed value

     7.1 Numeric

     Format   Name           Pattern             Value       Result
     C or c   Currency       {0:C2}, 1000.1      $ 1000.1    A currency value
     D or d   Decimal        {0:D5}, 30          00030       Integer digits with optional negative sign
     E or e   Exponential    {0,9:E2}, 120.2     1.20+E002   Exponential notation
     F or f   Fixed-point    {0,9:F2}, 120.2     120.2       Integral and decimal digits with optional negative sign
     G or g   General        {0,9:G2}, 120.2     120.2       The more compact of either fixed-point or scientific notation
     N or n   Number         {0,9:N1}, 1300.5    1,300,5    Integral and decimal digits, group separators, and a decimal separator with optional negative sign
     P or p   Percent        {0,9:P3}, .0903     9.03%       Number multiplied by 100 and displayed with a percent symbol
     R or r   Round-trip     {0,9:R}, 3.1416     3.1316      A string that can round-trip to an identical number
     X or x   Hexadecimal    {0,9:X4}, 31        001f        A hexadecimal string

    C# compiler at the Command Line

     csc File.cs -> Compiles Files.cs producing File.exe
     csc -target:library File.cs -> Compiles File.cs producing File.dll
     csc -out:My.exe File.cs -> Compiles File.cs and creates My.exe
     csc -define:DEBUG -optimize -out:File2.exe *.cs -> Compiles all the C# files in the current directory with optimizations enabled and defines the DEBUG symbol. The output is File2.exe
     csc -target:library -out:File2.dll -warn:0 -nologo -debug *.cs -> Compiles all the C# files in the current directory producing a debug version of File2.dll. No logo and no warnings are displayed
     csc -target:library -out:Something.xyz *.cs -> Compiles all the C# files in the current directory to Something.xyz (a DLL)

     8.1 Compiler Options Listed

     Option                     Purpose
     @                          Reads a response file for more options.
     -?                         Displays a usage message to stdout.
     -additionalfile                Names additional files that don't directly affect code generation but may be used by analyzers for producing errors or warnings.
     -addmodule                 Links the specified modules into this assembly
     -analyzer                  Run the analyzers from this assembly (Short form: -a)
     -appconfig                 Specifies the location of app.config at assembly binding time.
     -baseaddress               Specifies the base address for the library to be built.
     -bugreport                 Creates a 'Bug Report' file. This file will be sent together with any crash information if it is used with -errorreport:prompt or -errorreport:send.
     -checked                   Causes the compiler to generate overflow checks.
     -checksumalgorithm:<alg>   Specifies the algorithm for calculating the source file checksum stored in PDB. Supported values are: SHA1 (default) or SHA256.
     -codepage                  Specifies the codepage to use when opening source files.
     -debug                     Emits debugging information.
     -define                        Defines conditional compilation symbols.
     -delaysign                 Delay-signs the assembly by using only the public part of the strong name key.
     -deterministic             Causes the compiler to output an assembly whose binary content is identical across compilations if inputs are identical.
     -doc                       Specifies an XML Documentation file to generate.
     -errorreport               Specifies how to handle internal compiler errors: prompt, send, or none. The default is none.
     -filealign                 Specifies the alignment used for output file sections.
     -fullpaths                 Causes the compiler to generate fully qualified paths.
     -help                      Displays a usage message to stdout.
     -highentropyva             Specifies that high entropy ASLR is supported.
     -incremental               Enables incremental compilation [obsolete].
     -keycontainer              Specifies a strong name key container.
     -keyfile                   Specifies a strong name key file.
     -langversion:<string>      Specify language version: Default, ISO-1, ISO-2, 3, 4, 5, 6, 7, 7.1, 7.2, 7.3, or Latest
     -lib                       Specifies additional directories in which to search for references.
     -link                      Makes COM type information in specified assemblies available to the project.
     -linkresource              Links the specified resource to this assembly.
     -main                      Specifies the type that contains the entry point (ignore all other possible entry points).
     -moduleassemblyname            Specifies an assembly whose non-public types a .netmodule can access.
     -modulename:<string>       Specify the name of the source module.
     -noconfig                  Instructs the compiler not to auto include CSC.RSP file.
     -nologo                        Suppresses compiler copyright message.
     -nostdlib                  Instructs the compiler not to reference standard library (mscorlib.dll).
     -nowarn                        Disables specific warning messages
     -nowin32manifest           Instructs the compiler not to embed an application manifest in the executable file.
     -optimize                  Enables/disables optimizations.
     -out                       Specifies the output file name (default: base name of file with main class or first file).
     -parallel[+|-]             Specifies whether to use concurrent build (+).
     -pathmap                   Specifies a mapping for source path names output by the compiler.
     -pdb                       Specifies the file name and location of the .pdb file.
     -platform                  Limits which platforms this code can run on: x86, Itanium, x64, anycpu, or anycpu32bitpreferred. The default is anycpu.
     -preferreduilang           Specifies the language to be used for compiler output.
     -publicsign                Apply a public key without signing the assembly, but set the bit in the assembly indicating the assembly is signed.
     -recurse                   Includes all files in the current directory and subdirectories according to the wildcard specifications.
     -reference                 References metadata from the specified assembly files.
     -refout                    Generate a reference assembly in addition to the primary assembly.
     -refonly                   Generate a reference assembly instead of a primary assembly.
     -resource                  Embeds the specified resource.
     -ruleset:<file>            Specify a ruleset file that disables specific diagnostics.
     -subsystemversion          Specifies the minimum version of the subsystem that the executable file can use.
     -target                    Specifies the format of the output file by using one of four options: -target:appcontainerexe, -target:exe, -target:library, -target:module, -target:winexe, -target:winmdobj.
     -unsafe                    Allows unsafe code.
     -utf8output                    Outputs compiler messages in UTF-8 encoding.
     -warn                      Sets the warning level (0-4).
     -warnaserror               Reports specific warnings as errors.
     -win32icon                 Uses this icon for the output.
     -win32manifest             Specifies a custom win32 manifest file.
     -win32res                  Specifies the win32 resource file (.res).

    Control flow statements

     9.1 Switch

     switch (expression) {
     //expression may be integer, string or enum
     case expression:
         //statements
         break/ goto / return()

     case ..
     default
         //statements
         break/ goto / return()
     }

     9.2 If

     if (condition) {
         //statements
     } else {
         //statements
     }

    Loop

    10.1 While

    while (condition) {body}

    10.2 Do while

    do {body} while condition;

    10.3 For

    for (initializer; termination condition; iteration;) {
            //statements
    }

    10.4 For each

    foreach (type identifier in collection)  {
        //statements
    }

    Class Definition

    11.1 Class

    public | protected | internal | private
    abstract | sealed | static

    class className [:class/interfaces inherited from]

    11.2 Constructor

    [access modifier] className (parameters) [:initializer]

    initializer -base calls constructor in base class.
                 this calls constuctor within class.

    public class nameClass : Initializer {
        public className(dataType param1 , dataType param2, ...) : base(param1, param2)
        { constructor body }
    }

    11.3 Method

    [access modifier]
    static | virtual | override | new | sealed | abstract
    methodName (parameter list) { body }

    virtual – method can be overridden in subclass
    override – overrides virtual method in base class
    new – hides non-virtual method in base class
    sealed – prevents derived class from inheriting
    abstract – must be implemented by subclass

    Passing parameters:
        1. By default, parametres are passed by value
        2. Passing by reference: ref, in and out modifers

    To pass a parameter by reference with the intent of changing the value, use the ref, or out keyword. To pass by reference with the intent of avoiding copying but not changing the value, use the in modifier

    11.4 Property

    [modifier] <dataType> property name{
        public string BrandName
        {
            get { return brandName; }
            set { brandName = value; }
        }
    }

    Struct

    12.1 Defining a structure

    [attribute][modifier] struct name [:interfaces] { struct-body }

    12.2 Class vs Structure

       -> Classes are reference types and structs are value types
       -> Structures do not support inheritance
       -> Structures cannot have default constructor

    Enum

    13.1 Declaring enum variable

    enum <enumName> {
        enumeration list
    };

    enumName - Specifies the enumeration type name
    enumeration list is a comma-separated list of identifiers

    //Each of the symbols in the enumeration list stands for an integer value, one greater than the symbol that precedes it.

    Delegates

    //A delegate is a reference type variable that holds the reference to a method. The reference can be changed at runtime.

    14.1 Declaring delegates

    //Delegate declaration determines the methods that can be referenced by the delegate.

    delegate <return type> <delegate-name> <parameter list>

    14.2 Instantiating delegates

    //When creating a delegate, the argument passed to the new expression is written similar to a method call, but without the arguments to the method

    public delegate void printString(string s);
    printString ps1 = new printString(WriteToScreen);
    printString ps2 = new printString(WriteToFile);

    Events

    15.1 Declaring events

    //To declare an event inside a class, first a delegate type for the event must be declared.

    public delegate string MyDelegate(string str);

    //The event itself is declared by using the event keyword

    event MyDelegate MyEvent;

    15.2 Commonly used Control Events

    Event                                           Delegate

    Click, MouseEnter, DoubleClick, MouseLeave      EventHandler( object sender, EventArgs e)
    MouseDown, Mouseup, MouseMove                   MouseEventHandler(object sender, MouseEventArgs e)
                                                        e.X, e.Y – x and y coordinates
                                                        e.Button – MouseButton.Left, Middle, Right
    KeyUp, KeyDown                                  KeyEventHandler(object sndr, KeyEventArgs e)
                                                        e.Handled – Indicates whether event is handled.
                                                        e.KeyCode – Keys enumeration, e.g., Keys.V
                                                        e.Modifiers – Indicates if Alt, Ctrl, or Shift key.
    KeyPress                                        KeyPressEventHandler(object sender, KeyPressEventArgs e)