CS

[edit]

ide / keyboard shortcuts

[edit]
  • Snippy - gotdotnet.com - Manage snippet xml.
 #region Name_name
   ......   
 #endregion
 c:\windows\assembly in HD
 Access this via .net configuration (control panel). The Key is also found here
 ngen.exe install file.dll   - Nativa code generator (Can only gen signed code). Cannot decompile this.
 caspol.exe                  - Code access security policy
 fuslogvw.exe                - Assembly binding Log Viewer  (Run fuslogvw, run file.exe, refresh fuslogvw)
                             - Need to put a path in the log to disk.
 perfmon (windows standard)  - Look at ".NET CLR memory" as Performance object. Then select the specific Counter.
 Application Config File   -  "Add" application Config file (.ini file equivalent). Should be "app.config" filename.
                   <configuration>
                     <runtime>
                       <assemblyBinding
                         xmlns="urn:schemas-microsoft-com:asm.v1">
                         <probing privatePath="libs"/>
                         <publisherPolicy apply="no"/>
                         <dependentAssembly>
                           <assemblyIdentity name="AReverser" publicKeyToken="paste_the_public_token_here_from_.net_config"></assemblyIdentity>
                           <bindingRedirect oldVersion="2.0.0.0"
                                            newVersion="2.0.1.0"></bindingRedirect>
                         </dependentAssembly>
                       </assemblyBinding>
                     </runtime>
                   </configuration>
 Publish policy
 Machine.config  
csc /?     // Help
csc /out:file.exe /t:exe|library /r:ref1.dll,ref2.dll file.cs

Introduction

[edit]
?? expr  -> This is a "print(expr);". Shorthand for display returned value.
??? -> Need to check/not sure of the implementation
1.1 - Training Manual
2.0 - Visual Studio 2005
3.0 - Vista
Public Equals             - (Overloaded) Determines whether two Object instances are equal
Public GetHashCode        - hash function
Public GetType            - Get the type of the object
Public ReferenceEquals    - Determines if the specified Ibject are the same instance (same address)
Public ToString           - Returns a string that represent the object. Override this if needed.
                          - Special object method called internally if a function is requiring a string argument (and you passed the object as argument).
Protected Finalize        - Allows Object to attempt to free resources and perform other cleanup operation before the Object is reclaimed by garbage collection
Protected MemberWiseClone - Creates a shallow copy of the current Object
Value-type:     Stored in Stack - Exist only within the scope
  - Built-in Value Type
  - struct (User-Defined Value Types). Cannot have default constructor "()". Struct works just like Class (difference in memory allocation).
  - enum (Enumerations)
Reference-type: Stored in Heap - Garbage Collected - Allocated during "new" declaration.
  - All others / Objects, Class

Basic

[edit]
bool   - System.Boolean  - true/false
char   - System.Char     - Unicode 16 bit
sbyte  - System.SByte    - signed 8 bit integer
short  - System.Int16    - signed 16 bit integer
int    - System.Int32    - signed 32 bit integer
long   - System.Int64    - signed 64 bit integer
byte   - System.Byte     - unsigned 8 bit integer
ushort - System.UInt16   - unsigned 16 bit integer
uint   - System.UInt32   - unsigned 32 bit integer
ulong  - System.UInt64   - unsigned 64 bit integer
float  - System.Single   - 32 bit
double - System.Double   - 64 bit
Public    - World (default: enum, interface)
Protected - Including Derived
Internal  - within assembly -> .dll/.exe
Private   - same class Class only (default: struct, class). Note: In C++ this is public.
Protected Internal - protected OR internal (not and)
 implicit:  (small) char -> int  -> float  (big)
 explicit:  (small) char <- int  <- float  (big)   - Bec some information could be lost

 int    x=25;    double d=x;         // no error
 double x=36.7;  int    z=(int)x;    // need to explicitly cast

 dog = (Dog)a;
 dog = a as Dog;                     // same as above     (Dog, Cat is OBJECT)

 if(a is Cat) { }                    // dynamic casting is happening
 if(a.GetType()==typeof(Cat)) { }    // same as above 

 Overload implicit/explicit Conversion (if the objects are not related/inherited):
    static public implicit operator byte(digit d) {     // byte is object, digit is object
      return(d.Data);
    }
    static public explicit operator digit(byte b) {     // bec digit is smaller than byte
      return(new digit(b))
    }
   
 objx s1 = new objx("ABC");
 objx s2 = s1;
 objx s3 = new objx("ABC");
 ?? object.referenceEquals(s1,s2)      // boolean TRUE  (object.equals) is the same as referenceequals???
                                       // This is identity
 ==  ->  object.equals                 // Equality
 ?? object.equals(s1,s3);              // identity is FALSE, Equality is TRUE (Overload the .equals and == operator)

 static bool operator==(objx lhs, objx rhs) {
   if((object)lhs==null) return false;
   return(lhs.Equals(rhs);
 }
 public override bool Equals(object obj) {      // use object so that polymorphism will take effect
   if(obj==null || obj.GetType()!=this.GetType)) return false;
     //         || (!(obj is student))  )       // Another way
   student arg=obj as student;
   return(this.name == arg.name &&  ..code.. );
 }

 Guidelines:
    * If overriding Equals override GetHashCode
    * If overloading ==, override Equals to use the same algorithm
    * If implementing IComparable, implement Equals
    * Equals, GetHashCode, and == operator should never throw exceptions
    * Overload != when overloading ==. != should be a ! of Equals.



Objects & Syntax

[edit]
non-static - instance method - object
 foo(ref int x) { }    // as a pointer
 foo(out int x) { }    // out is out only. ref is in/out. default is in only.

 const int rows=45;    // constant
 int x;
 object o=x;           // boxing
 int y=(int)o;         // unbox

 virtual public int methodname() { }     // identifies an overloadable method (base class)
 public override int methodname() { }    // derived class override. Can only override virtual method.
 public new int methodname() { }         // New methodname (not derived). Difference in polymorphic behavior.
 public abstract void method();          // Method is not defined in base class, it must be defined in derived class.
 public sealed override void method();   // Cannot use this in Base class. Any derived class cannot override Foo.
 public static void method();            // Can only accessed via the classname!
 public readonly int var;                // readonly, can be initialized in constructor
 public const int var=3;                 // const: compile time constant. Const is always static.
 base.foo();                             // Calls the base ???

 Type t=obj.Gettype;                     // Gets the type ???
 params char[]                           // variable number of arguments ???

 yield return(val);                      // New in 2.0. used inside IEnumerable function.
using System;
namespace Days1  {
    public class Employee {                          // : Object   (derived from Object, implied)
        // Fields
        public static int globid=2;                  // This is a built in constructor.
        public string sex="Male";                    // This is also a constructor (default)
        private string name;

    //  public static Employee() { }                 // static constructor are called after a program begins running but before the 1st instance of the class is created.
        public Employee() : this("Noname") { }       // Default Constructor, calls another constructor
        public Employee(string name) {               // Constructor
          this.name = name;
        }                                         

        public string getname {                      // Property
            set { name=value+" OK"; }                // value is a reserved word
            get { return("Mr "+name); } 
        }
        public int func_id(int id) {                 // Method
            globid = id;
            return (globid);
        }
        public int func_id() {                       // override for no arguments
            return (globid);
        }
        public static Employee operator +(Employee c1, Employee c2) { }    // Creating operators
    }
    public class Program
    {
        public static void Main()
        {              // Main Function
            Employee aa = new Employee();
            Employee bb = new Employee("Fred");
            Console.WriteLine("Hello {0} {1}", aa.getname, aa.func_id(43));   // Hello Mr Noname 43
            Console.WriteLine("Hello {0} {1}", bb.getname, bb.func_id());     // Hello Mr Fred 43
                                                                              // THIS IS A STATIC example!
            Console.WriteLine(Employee.globid);     // This is the way to access static members
            aa.sex = "Female";                      // Write to a member directly
        }
    }
}
* Do not put public/private/protected in interface
interface ICDPlayer {                                 
  void Play(short PlayTrackNum);
  short CurretTrack { get; set; }
}
public class Device : ICDPlayer { ... }
public class name : DeriveBase, [Iinterface1, Iinterface2, Ietc..] { .... }
abstract class Animal { }         // Cannot use abstract class in "new". 
                                  // Use this when base class does not implement the member.
                                  // Abstract has code but it is not complete (interface doesnt have any code)
sealed class Classname { }        // Cannot be inherited
ushortAge = Convert.ToUInt16(longAge);     // Convert class
 class Singleton {
   private Singleton() { }            // Need to declare as private
   static private Singleton thedata;
   static public Singleton GetSingleton {
     get {   if (thedata == null)
               thedata = new Singleton();       // will only be executed ONCE
             return thedata; 
         }
   }
 }
 ....
 Singleton s1=Singleton.GetSingleton;
 Singleton s2=Singleton.GetSingleton;    // s1 is the same as s2
 Singleton s3=new Singleton();           // This is INVALID bec the constructor is private!

Using / enum / pointers

[edit]
 System.IO.FileStream aFileStream;
     vs
 using System.IO;
 FileStream aFileStream;
     vs
 using alias1 = System.IO.FileStream
 alias1 aFileStream;

 // Temporary Resource Usage Pattern (note: Resource is a user object that implements IDisposable)
 using (Resource r1 = new Resource()) {      // battle with compile time error. This is a better way of coding.
    r1.Foo();
 }
       -is the same as-
 Resource r1 = new Resource();               // battle with runtime error
 try { r1.Foo() }
 finally { 
   if(r1 != null) ((IDisposable)r1).Dispose();
 }
 enum Weekdays { Monday, Tuesday, Wednesday, Thursday, Friday };     // declare enum type (Cannot do this in function/method)
      ....
 Weekdays wd;
 string st = Console.ReadLine();                      // Get input
 wd=(Weekdays)Enum.Parse(typeof(Weekdays), st);       // Convert the enum string
 if (wd == Weekdays.Friday) { .... }                

 [Flags] enum Weather : ushort { Sunny=1, Cloudy=2, Rain=4, Snow=8,Flog=16};
 Weather ww;
 ww = Weather.Sunny | Weather.Cloudy;     // the enum holds both
 ?? ww.ToString()                         // Sunny, Couldy
byte bref;
unsafe {    // need to uncheck in project settings
  fixed (byte bp=&bref) {
    ...code...
  }
 }
[Dllimport("legacy.dll")]
void Algo(  );
Algo();

Arrays

[edit]
 objx[] xx = new objx[sizeN] { new objx(...), new objx(...) };    // Array of objects
 int[] intArray = new int[sizeN];
 int[,] multidim = new int[ , ] { {1,1,1},{2,2,2} };     // or int[,,]
 int ex = multidim[1,2];                                 // Layed out linearly in memory (could be accessed via single dim array)
 int[][] jaggedarray = new int[4][];                     // jagged array
 for(i=0;i<jaggedarray.Length;i++)
   jaggedarray[i]=new int[++dim];
 foreach(int[] rows in jaggedarray)
   foreach(int col in rows) { }

 IEnumerator iter = intarray.GetEnumerator();
 while(iter.MoveNext()) { ?? iter.Current } 
 iter.Reset();    // set the enumerator at the top. (Cannot modify the source object if you are currently using the enumerator)

 Array.Sort(intArray);         // boxed (slow). Modifies the intArray.
 Array.Sort<int>(intArray);    // faster, more efficient (parameterized)
                               // Make objects IComparable<parameterized> (interface) so that sort could be used. Use the standard design pattern/template.
 Array.Sort<int>(intArray, new DescComparator());   // DescComparator is a IComparable ???
 Array.Reverse<int>(intArray); // Reverse it

 ArrayList emplist = new Arraylist();                  // Generic. You could add emplist.add(3.2);
 Employee e = new Employee(...);
 emplist.add(e);
 emplist.add(new Employee(...));
 emplist.Insert(idx, new Employee(...));
 emplist.Sort();           // No parameterized implementation for ArrayList.
 ?? emplist.Indexof(e)     // integer
 ?? emplist.Contains(e)    // bool
 ?? emplist[idx]

 IEnumerator curr = emplist.GetEnumerator();              // This is object
 IEnumerator<Employee> curr = emplist.GetEnumerator();    // Specific to employee (if parameterized)
 // curr.Current.Method could be used
 as IvalueType ???

 List<Employee> emplist = new List<Employee>();     ???      // specific to Employee!!

 Array.ForEach<int>(intArray, new Action<int>(delegate(int arg) { ++arg; } ) );   // However, the array is not changed bec "int arg" is passed as values.

 public int CompareTo(Object obj) {        // standard sort compareto function
  if(obj==null) return 1;
  if(!(obj is classname)) throw new ArgumentException();
  // Do comparison, -1 if this<obj, 0 if this==obj, 1 if this>obj
 }

Hash

[edit]
 Hashtable hh = new Hashtable();
 hh["aa"] = "1st";
 hh["aa"] = "2nd";           // This is ok. Using .add willnot work
 hh["aa"] = objx;            // Could be any object
 hh[objx] = "3rd";           // Key could also be anything. In this case the key is the object (it's NOT calling the .toString internally)

 ?? hh["aa"]                 // "2nd"
 ?? hh.ContainsKey("cc"))       // False. hh.Contains() actually calls hh.ContainsKey()
 foreach (object key in hh.Keys)                         // simpliest way
    ?? hh[key]                                           // key is automatically converted to string
 foreach (DictionaryEntry d in hh) {                     // another method
    Console.WriteLine("{0} = {1}", d.Key, d.Value);      
    Console.WriteLine("{0} = {1}", d.Key, hh[d.Key]);    // Same as above, but above is more efficient bec data is already retrieved
 }
 IDictionaryEnumerator ky = hh.GetEnumerator();          // another method
 while(ky.MoveNext()) 
    Console.WriteLine("{0} = {1}", ky.Key, ky.Value);

 SortedList hh = new SortedList();        // SortedList example. Use this if you want "sort(keys(%hh))" in perl
 hh["nn"] = "value";
 foreach (string ss in hh.Keys)           // Can use string directly. This is already sorted
   ?? hh[ss]       
 
 Dictionary<string, string> dict = new Dictionary<string, string>();      // Dictionary example
 dict["nn"] = "value";
 foreach (string ss in dict.Keys)         // Can use string directly
   ?? dict[ss]       

 Hashtable table = new Hashtable();
 foreach  (Employee emp in emplist)       // ie, if Employee is IEnumerator
   table.add(emp.GetHashCode(), emp);     // Cannot .add duplicate key. Implicitly call .GetHashCode()
 ?? table.ContainsKey(key);
 ?? table.ContainsValue(value);

Exceptions / Error

[edit]
try {
  ...code...
} catch(IndexOutOfRangeException e) {      // THIS SHOULD BE SPECIFIC
  ?? e.Message
} catch(Exception e ) { }                  // THIS is ANY exception
  throw new IndexOutOfRangeException();
} finally {
  // place code that runs after try to catch runs
}


Mixing Managed/Unmanaged

[edit]
  • System.Byte
  • System.SByte
  • System.Int16
  • System.UInt16
  • System.Int32
  • System.UInt32
  • System.Int64
  • System.IntPtr
  • System.UintPtr
  • System.Array Converts to a C-style or a SAFEARRAY.
  • System.Boolean Converts to a 1, 2, or 4-byte value with true as 1 or -1.
  • System.Char Converts to a Unicode or ANSI character.
  • System.Class Converts to a class interface.
  • System.Object Converts to a variant or an interface.
  • System.Mdarray Converts to a C-style array or a SAFEARRAY.
  • System.String Converts to a null-terminated string or to a BSTR.
  • System.Valuetype Converts to a structure with a fixed memory layout.
  • System.Szarray Converts to a C-style array or a SAFEARRAY.
Wtype.h Type    C# Type
HANDLE          int
BYTE            byte
SHORT           short
WORD            ushort
INT             int
UINT            uint
LONG            int
ULONG           uint
BOOLEAN         int
CHAR            char
FLOAT           float
DOUBLE          double
LPSTR(and most  String for in, StringBuilder for inout
other string 
types)

String / Formats / Regular Expressions

[edit]
  • Using string for non-changing string. Use stringbuilder for strings that change (efficient).
  • No limit for string length (memory limit only)
 starr = new string[] { "txt1", "txt2", "txt3" };
 ?? starr.Length                     // Number of elements
 string name;                        // name has null value
 (name="")  == (name=string.Empty)   // These are equivalent
 ((string)e.Current).TrimStart('a')  // implicitly convert e.Current to a string.
 ?? "Hello"[2];                      // "l" 3rd character
 ?? @"C:\Docs\Source";               // rather than "C:\\Docs\\Source".
 ?? "\u0068ello "+"world";           // "Hello world"

 int ii=int.Parse("12,345", NumberStyles.AllowThousands | NumberStyles.CurrencySymbol, cultinfo);          // string to number. 2nd argument is optional. It's enum. cultinfo is CultureInfo
 string ss=String.Format("{0:###-##-####}",34);
 int    ii=String.Compare(str1, "Hello");
 string ss=String.Join(",", words);       // also, string s2 = String.Join(",", (new string[] {"a","b"}));
 string ss=(100).ToString("C");           // "$100.00",  same as Console.WriteLine("{0:C}", 100);
 string ss="hello".ToUpper();             // .ToLower()
 string ss=" hello ".Trim();
 string ss="hello".PadLeft(20,'-');
 string[] words=line.Split(null);         // returns an array, separate by whitespace

 StringBuilder sb=new StringBuilder("string");    // Ultra fast!!! (if you manipulate strings a lot);
 sb.Append("added text");
 if(sb.ToString() == "abc");                      // Checks if sb equals "abc" 
 if(sb.Equals(new StringBuilder("abc")));         // Another Way

 string[] sx = Directory.GetCurrentDirectory().Split(Path.DirectorySeparatorChar);    // Path.DirectorySeparatorChar=='\\'
 foreach(string sx1 in sx) ?? sx1;

DateTime curdate = DateTime.Now;             // This is a struct so no need for "new"
Console.WriteLine("{0:C}", 100);             // $100.00
Console.WriteLine("{0:d}", (new DateTime(2000,1,10,0,0,0)));   // "1/10/2000"
     // d-"MM/dd/yyyy"   D-"DD MMMM YYYY"  f-"DD MMMM YYYY HH:MM"   F-"DD MMMM YYYY HH:mm:SS"
     // C-"$nn,nnnn.nn"
CultureInfo ci = new CultureInfo("En-GB");           // Use Cultures
 Regex ex = new Regex("ab+", RegexOptions.IgnoreCase);   // create the regular expression. RegexOptions is enum
 string line = "abbbabababbfabrbdbsbaaab";
 foreach (object oo in ex.Matches(line))                 // .GetEnumerator() is implicitly called in foreach
    Console.WriteLine(oo);                               // .toString is implicitly called bec writeline arg type is string.

 MatchCollection mc = ex.Matches(line);                  // Long method
 IEnumerator e = mc.GetEnumerator();
 while (e.MoveNext()) Console.WriteLine(e.Current);

 if(ex.IsMatch(line)) { }        // Regular expression matched

Memory and Garbage Collection

[edit]
class Foo {
  ~Foo() { fs.close(); }     // implicitly called
}
objx a1 = new objx();
a1=null;                  // The memory allocated for the "new" object is now ready for garbage collection.
- -----------------------
- | Finalize Queue
- |   - objects are added here the same time as in Root Ref if the object has destructor
- -----------------------
- |
- |    Managed Heap
- |
- -----------------------
- | ---------------------
- | |  Freachable Queue     // objects from Finalize Queue are moved here during GC
- | ---------------------
- | Root Ref
- -----------------------
GC.Collect([int Generation])
GC.GetGeneration(Object obj);   // query the generation of an object
GC.MaxGeneration(int);


objx sr = new objx();
WeakReference wr = new WeakReference(sr);
sr=null;   // deallocate it
...  //  GC.Collect();  // dispose
if( (sr=(objx)wr.Target) != null ) {     // or check if(wr.isAlive) { }
   treat_sr_normally();
} else { 
   sorry_no_more_sr();
}
unsafe {
  int i=3;
  int* ip=&i;
  fixed (byte* bp=buf) {     // buf is defined somewhere
    *(bp+3) = 34;
    ...etc
  }
   

Data Stream and Files

[edit]
 Read, Write, Seek       // Fundamental Stream Operations
   - CanRead, CanWrite, CanSeek   // properties
   - Flush()
   - Close()     // performs implicit flush
 NetworkStream, BufferedStream, memoryStream, FileStream, CryptoStream    // Stream Classes
 BinaryReader, BinaryWriter     // Binary classes
 TextReader, TextWriter         // character classes
 StreamReader, StreamWriter     // derived from TextReader/Writer
 StringReader, StringWriter     // derived from TextReader/Writer that uses StringBuilder class

 FileStream -  Class for Reading and Writing to Files
   FileMode   - Open, Append, Create (enum)
   FileAccess - Read, ReadWrite, Write (enum)
   FileShare  - None, Read, ReadWrite, Write (enum)

 File - Class with methods for Create, Copy, Delete, Move, Open
 FileInfo - Just like File Class but faster when reusing the object.
 Directory     - Class for Directories
 DirectoryInfo - Faster than Directory bec one security check

 Path - Helper Class for Paths

 FileSystemWatcher          - Class used to Monitor a File System
 IsolatedStorageFile        - Class for Isolated Storage 
 IsolatedStorageFileStream

 .Begin* - Asynchronous methods
 .End*   - Asynchronous methods
 if(!File.Exists("filename")) { }    // exists
 FileStream fs = new FileStream("filename", FileMode.CreateNew);   // FileMode.Open
 BinaryWriter w = new BinaryWriter(fs);
 w.write( (int)45 );
 w.Close();  fs.Close();
 BinaryReader r = new BinaryReader(fs);
 ?? r.ReadInt32()

 FileInfo fi = new FileInfo(Path.Combine(dir,subdir));
 if(!fi.Exists) { };
 using(StreamReader sr = fi.OpenText()) { }

 FileStream astream = File.Create("name");   // Another way

 DirectoryInfo dir = new DirectoryInfo(".");
 foreach(FileInfo f in dir.Getfiles("*.*")) {
   ?? f.Fullname;
   ?? f.Length;
   ?? f.CreationTime;
 }

 FileSystemWatcher watcher = new FileSystemWatcher();       // Create ================
 watcher.Path = "pathstring";  // or args[0];               // Configure =============
 watcher.Filter = "*.txt"
 watcher.NotifyFilter = NotifyFilters.FileName;             // this is enum
 watcher.Renamed += new RenamedEventHandler(OnRenamed);     // this is the lightningbolt! on ide
 watcher.Created += new FileSystemEventHandler(OnChanged);
 watcher.IncludeSubdirectories = true;                      // include subdirectory
 watcher.EnableRaisingEvents = true;                        // Begin Watching ========
 public static void OnRenamed(object s, RenamedEventsArgs e) {
   ?? e.OldFullPath
   ?? e.FullPath
 }

 IsolatedStorageFile iso = IsolatedStorageFile.GetUserStoreForDomain();
 IsolatedStorageFileStream isoStream - new IsolatedStorageFileStream("MyStuff.txt", etc);
    using(StreamWriter wr = new StreamWriter(isoStream)) { wr.WriteLine("Stuff"); }
 IsolatedStorageFile isoread = IsolatedStorageFile.GetUserStoreForDomain();
    string[] isoFiles = isoread.GetFilenames("MyStuff.txt");

Serialization

[edit]
[Serializable] public class Myclass {
    [NonSerialized] int _cachSize;        // Skip specific members
    ....
}
[Serializable] public class ExampleFoo : ISerializable {              // Example
  public int i,j,k;
  public ExampleFoo() {}
  internal ExampleFoo(SerializationInfo si, StreamingContext context) {
    i=si.GetInt32("i"); j=si.GetInt32("j"); k=si.GetInt32("k");
  }
  public void GetObjectData(SerializationInfo si, StreamingContext context) {
    si.AddValue("i",i); si.AddValue("j",j); si.AddValue("k",k); 
    Type t=this.GetType();
    si.AddValue("TypeObj", t);
  }
}
FileStream fs = File.Create("Person.xml");          // SOAP example
SoapFormatter sf = new SoapFormatter();
ArrayList al = new ArrayList();       // Then put mutliple objects in al. For this example, Person objects.
sf.Serialize(fs, al);
fs.Close();                           // DONE
fs = File.OpenRead("Person.xml");
ArrayList al = (ArrayList)sf.Deserialize(fs);    // READIT

Delegates & Events

[edit]
  public class objx {                           // Sample Object
    public string foo(int id) {                
      return (id.ToString() + " from foo");
   }
  }

  delegate string MyDelegate1( int ii );        // syntax. "int ii" bec foo() takes in int. string bec foo() returns string.

      Mydelegate1 myhandler = null;             // This portion is just semantics. It wont work, refer to SwitchandLight for a working one.
      function connecto(MyDelegate1 del1) {
        myhandler += del1;                      // adds delegates 
      }

  objx oo = new objx();
  MyDelegate1 dd = new MyDelegate1(oo.foo);
  ?? dd(21);          // Call the delegate. This will return "21 from foo"

Web Services / Request / Sockets

[edit]
Using System.Xml;
...
USZip zipper = new USzip();                   // USZip is created by wsdl automatically. Need to add "System.WebService" as reference
XmlNode node = zipper.getInfoByZIP(97210);    // Then do something with node
[WebMethod] public String myfunc() { return("Hello World"); }
 WebRequest request = WebRequest.Create("localhost:3427");
 reqyest.Credentials = CredentialCache.DefaultCredentials;
 WebResponse response = request.GetResponse();
 ?? ((HttpWebResponse)response).StatusDescription

 WebBrowser1.Url = new Uri(addr);

 For Socket... see sockets example from Lab and manual

ADO.NET

[edit]
 SQL <---> OLEdb
 SqlConnection Class
 SqlCommand Class
 SqlAdapter Class
 OLEdb Class
   using(SqlConnection mysql = new SqlConnection(@"Connection String")) {     // to determine connection string: (New Web App: Choose Item: SQLConnection, drag to desktop, goto properties "Connection String", then you should see "Add Connection" window)
      ?? mysql.ConnectionString
      string ssql = "select * from region";
      SqlDataAdapter adaptor = new SqlDataAdaptor(ssql, mysql);
      DataSet mydataset = new DataSet();
      adaptor.Fill(mydataset, "Regionx");           // Name of the table that gets created?
      ?? mydataset.Tables["Regionx"].Rows.Count

      adaptor.SelectCommand.CommandText = "select * from customers";    // Another query
      foreach(DataRow mydatarow in mydataset.Tables["Regionx"].Rows)
        ?? myDataRow["RegionID"].ToString();    // RegionID is a field

      adaptor.update  -> Update the database

      DataView mydataview = mydataset.Tables["Regionx"].DefaultView;
      mydataview.Sort = "Country";
      mydataview.RowFilter = .....

   }