2010 - C# 4.0 in a Nutshell 4ed (O'Reilly)

8/12/2019 2010 - C# 4.0 in a Nutshell 4ed (O'Reilly)

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Avoiding conflicts

,I\RXUHDOO\ZDQWWRXVHDQLGHQWLILHUWKDWFODVKHVZLWKDNH\ZRUG\RXFDQGRVRE\

TXDOLI\LQJLWZLWKWKH@SUHIL[)RULQVWDQFH

class class {...} // Illegalclass @class {...} // Legal

7KH @V\PEROGRHVQWIRUPSDUWRIWKHLGHQWLILHULWVHOI6R@myVariableLVWKHVDPHDVmyVariable

7KH@SUHIL[FDQEHXVHIXOZKHQFRQVXPLQJOLEUDULHVZULWWHQLQRWKHU1(7ODQJXDJHVWKDWKDYHGLIIHUHQWNH\ZRUGV

C#Basics


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8 bits 27to 271

short Int16 16 bits 215to 2151

int Int32 32 bits 231to 2311

long Int64 L 64 bits 263to 2631

Integralunsigned

byte Byte 8 bits 0 to 281

ushort UInt16 16 bits 0 to 2161

uint UInt32 U 32 bits 0 to 2321

ulong UInt64 UL 64 bits 0 to 2641

Real

float Single F 32 bits (~1045to 1038)

double Double D 64 bits (~10324to 10308)

decimal Decimal M 128 bits (~1028

to 1028

)

2IWKHLQWHJUDOW\SHVint DQGlongDUHILUVWFODVVFLWL]HQVDQGDUHIDYRUHGE\ERWK&

DQGWKHUXQWLPH7KHRWKHULQWHJUDOW\SHVDUHW\SLFDOO\XVHGIRULQWHURSHUDELOLW\RU

ZKHQVSDFHHIILFLHQF\LVSDUDPRXQW

2IWKHUHDOQXPEHUW\SHV float DQGdoubleDUHFDOOHGIORDWLQJSRLQWW\SHV DQGDUH

W\SLFDOO\XVHGIRUVFLHQWLILFFDOFXODWLRQV7KHdecimalW\SHLVW\SLFDOO\XVHG IRUILQDQFLDO FDOFXODWLRQV ZKHUH EDVHDFFXUDWH DULWKPHWLF DQG KLJK SUHFLVLRQ DUH

UHTXLUHG

Numeric Literals

C#Basics


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float f =1.0F;

D double double d =1D;

M decimal decimal d =1.0M;

U uint or ulong Combinable with L uint i =1U;

L long or ulong Combinable with U ulong i =1UL;

7KHVXIIL[HV UDQGL DUHUDUHO\QHFHVVDU\EHFDXVHWKHuint longDQG ulongW\SHVFDQ

QHDUO\DOZD\VEHHLWKHULQIHUUHGRULPSOLFLWO\FRQYHUWHGIURPint

long i =5; // Implicit lossless conversion from int literal to long

7KH D VXIIL[ LV WHFKQLFDOO\ UHGXQGDQW LQ WKDW DOO OLWHUDOV ZLWK D GHFLPDO SRLQW DUHLQIHUUHGWREHdouble$QG\RXFDQDOZD\VDGGDGHFLPDOSRLQWWRDQXPHULFOLWHUDO

double x =4.0;

7KH FDQGMVXIIL[HVDUHWKHPRVWXVHIXODQGVKRXOGDOZD\VEHDSSOLHGZKHQVSHFL


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Complement ~0xfU 0xfffffff0U

& And 0xf0 &0x33 0x30

| Or 0xf0 |0x33 0xf3

^ Exclusive Or 0xff00 0x0ff0 0xf0f0

C#Basics


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Internal representation Base 2 Base 10

Precision 1516 significant f igures 2829 significant f igures

Range (~10324to ~10308) (~1028to ~1028)

Special values +0, 0, +, , and NaN None

Speed Native to processor Non-native to processor (about 10 times slower thandouble)

Real Number Rounding Errors

float DQGdouble LQWHUQDOO\ UHSUHVHQW QXPEHUV LQ EDVH )RU WKLV UHDVRQ RQO\

QXPEHUVH[SUHVVLEOHLQEDVHDUHUHSUHVHQWHGSUHFLVHO\3UDFWLFDOO\WKLVPHDQVPRVW

OLWHUDOVZLWKDIUDFWLRQDOFRPSRQHQWZKLFKDUHLQEDVHZLOOQRWEHUHSUHVHQWHGSUHFLVHO\)RUH[DPSOH

float tenth =0.1f; // Not quite 0.1float one =1f;Console WriteLine (one - tenth * 10f); // 1 490116E-08

C#Basics
http://0.0.0.0/http://www.ieee.org/


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Single quote 0x0027

\" Double quote 0x0022

\\ Backslash 0x005C

\0 Null 0x0000

\a Alert 0x0007

\b Backspace 0x0008

\f Form feed 0x000C

\n New line 0x000A

\r Carriage return 0x000D

\t Horizontal tab 0x0009

\v Vertical tab 0x000B

7KH\uRU\x HVFDSHVHTXHQFHOHWV\RXVSHFLI\DQ\8QLFRGHFKDUDFWHUYLDLWVIRXU

GLJLWKH[DGHFLPDOFRGH

char copyrightSymbol =\u00A9;


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All reference types null

All numeric and enum types 0

char type \0

bool type false


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G h l Y


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>= Greater than or equal

to

x >=y Yes

is Type is or is subclass of x is y No

as Type conversion x as y No

Equality == Equals x ==y Yes

!= Not equals x !=y Yes

Logical And & And x &y Yes

Logical Xor ^ Exclusive Or x y Yes

Logical Or | Or x |y Yes

Conditional And && Conditional And x &&y Via &

Conditional Or || Conditional Or x ||y Via |

Null coalescing ?? Null coalescing x ??y No

Conditional ?: Conditional isTrue ?thenThisValue : elseThisValue

No

Assignment = Assign x =y No

*= Multiply self by x *=2 Via *

/= Divide self by x /=2 Via /

+= Add to self x +=2 Via +

= Subtract from self x =2 Via

>

&= And self by x &=2 Via &

= Exclusive-Or self by x =2 Via ^ |= Or self by x |=2 Via |

Lambda => Lambda x =>x + 1 No


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Preceding the keyword class Attributesandclass modifiers. The non-nested class modifiers are public, internal,abstract, sealed, static, unsafe, and partial

Following YourClassName Generic type parameters, a base class, and interfaces

Within the braces Class members(these are methods,properties, indexers, events, fields, constructors,operator functions, nested types, and a finalizer)

7KLVFKDSWHUFRYHUVDOORIWKHVHFRQVWUXFWVH[FHSWDWWULEXWHVRSHUDWRUIXQFWLRQVDQG

Static modifier static

Access modifiers public internal private protected


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p p p

Inheritance modifier new

Unsafe code modifier unsafe

Read-only modifier readonly

Threading modifier volatile

The readonly modifier

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UHDGRQO\ILHOGFDQEHDVVLJQHGRQO\LQLWVGHFODUDWLRQRUZLWKLQWKHHQFORVLQJW\SHV

FRQVWUXFWRU

Field initialization

)LHOGLQLWLDOL]DWLRQLVRSWLRQDO$QXQLQLWLDOL]HGILHOGKDVDGHIDXOWYDOXH0\0 nullfalse)LHOGLQLWLDOL]HUVUXQEHIRUHFRQVWUXFWRUV

public int Age =10;

Declaring multiple fields together

)RU FRQYHQLHQFH \RX PD\ GHFODUH PXOWLSOH ILHOGV RI WKH VDPH W\SH LQ D FRPPD

VHSDUDWHGOLVW7KLVLVDFRQYHQLHQWZD\IRUDOOWKHILHOGVWRVKDUHWKHVDPHDWWULEXWHVDQGILHOGPRGLILHUV)RUH[DPSOH

static readonly int legs =8, eyes =1;

Methods

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GDWDIURPWKHFDOOHUE\VSHFLI\LQJSDUDPHWHUVDQGRXWSXWGDWDEDFNWRWKHFDOOHUE\

VSHFLI\LQJD UHWXUQW\SH$PHWKRGFDQVSHFLI\D voidUHWXUQW\SHLQGLFDWLQJWKDWLW

GRHVQW UHWXUQ DQ\ YDOXH WR LWV FDOOHU $ PHWKRG FDQ DOVR RXWSXW GDWD EDFN WR WKH


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Static modifier static



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Inheritance modifiers new virtual abstract override sealed

Unmanaged code modifiers unsafe extern

Read-only and calculated properties

$SURSHUW\ LVUHDGRQO\LILWVSHFLILHVRQO\DgetDFFHVVRUDQGLWLVZULWHRQO\LILW

VSHFLILHVRQO\DsetDFFHVVRU:ULWHRQO\SURSHUWLHVDUHUDUHO\XVHG

$ SURSHUW\ W\SLFDOO\ KDV D GHGLFDWHG EDFNLQJ ILHOG WR VWRUH WKH XQGHUO\LQJ GDWD

+RZHYHUDSURSHUW\FDQDOVREHFRPSXWHGIURPRWKHUGDWD)RUH[DPSOH

decimal currentPrice, sharesOwned;

public decimal Worth

{ get {return currentPrice * sharesOwned; }}

Automatic properties

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UHDGVDQGZULWHVWRDSULYDWHILHOGRIWKHVDPHW\SHDVWKHSURSHUW\$QDXWRPDWLF

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public class Stock{ ... public decimal CurrentPrice {get; set; }}

7KHFRPSLOHUDXWRPDWLFDOO\JHQHUDWHVDSULYDWHEDFNLQJILHOGRIDFRPSLOHUJHQHUDWHG

QDPHWKDWFDQQRWEHUHIHUUHGWR7KHsetDFFHVVRUFDQEHPDUNHG privateLI\RXZDQW

WRH[SRVHWKHSURSHUW\DVUHDGRQO\WRRWKHUW\SHV$XWRPDWLFSURSHUWLHVZHUHLQ


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Inheritance modifier new

Static Constructors$ VWDWLFFRQVWUXFWRUH[HFXWHVRQFHSHU W\SHUDWKHUWKDQRQFHSHULQVWDQFH$W\SH

FDQGHILQHRQO\RQHVWDWLFFRQVWUXFWRUDQGLWPXVWEHSDUDPHWHUOHVVDQGKDYHWKH

VDPH QDPH DV WKH W\SH

CreatingT

ypes
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Unmanaged code modifier unsafe

Partial Types and Methods

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FRPPRQVFHQDULRLVIRUDSDUWLDOFODVVWREHDXWRJHQHUDWHGIURPVRPHRWKHUVRXUFH

HJDQ;6DQGIRUWKDWFODVVWREHDXJPHQWHGZLWKDGGLWLRQDOKDQGDXWKRUHG

PHWKRGV)RUH[DPSOH

// PaymentFormGen.cs - auto-generatedpartial class PaymentForm {... }

// PaymentForm.cs - hand-authoredpartial class PaymentForm {... }

(DFKSDUWLFLSDQWPXVWKDYHWKHpartialGHFODUDWLRQWKHIROORZLQJLVLOOHJDOpartial class PaymentForm {}class PaymentForm {}

CreatingT

ypes


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Gatekeeper class for all CRUD operations DataContext ObjectContext

Type to represent one side of a relationship property, whenthat side has a multiplicity of one

EntityRef EntityReference

Default strategy for loading relationship properties Lazy Explicit

Construct that enables eager loading DataLoadOptions .Include()

Building Query Expressions

6RIDULQWKLVFKDSWHUZKHQZHYHQHHGHGWRG\QDPLFDOO\FRPSRVHTXHULHVZHYH

GRQH VR E\ FRQGLWLRQDOO\ FKDLQLQJ TXHU\ RSHUDWRUV $OWKRXJK WKLV LV DGHTXDWH LQ

PDQ\VFHQDULRVVRPHWLPHV\RXQHHGWRZRUNDWDPRUHJUDQXODUOHYHODQGG\QDP

LFDOO\FRPSRVHWKHODPEGDH[SUHVVLRQVWKDWIHHGWKHRSHUDWRUV

,QWKLVVHFWLRQZHOODVVXPHWKHIROORZLQJProductFODVV

[Table]public partial class Product{ [Column(IsPrimaryKey=true)]public int ID;


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[Co u ( s a y eyt ue)]pub c t D; [Column] public string Description; [Column] public bool Discontinued;

[Column] public DateTime LastSale;}

Delegates Versus Expression Trees

5HFDOOWKDW

/RFDOTXHULHVZKLFKXVHEnumerableRSHUDWRUVWDNHGHOHJDWHV

,QWHUSUHWHGTXHULHVZKLFKXVHQueryableRSHUDWRUVWDNHH[SUHVVLRQWUHHV

:HFDQVHHWKLVE\FRPSDULQJWKHVLJQDWXUHRIWKHWhereRSHUDWRULQEnumerableDQG

Queryable

public static IEnumerableWhere(this IEnumerablesource, Funcpredicate)

public static IQueryableWhere(thisIQueryablesource Expressionpredicate)


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http://www.albahari.com/expressions/


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Returns a subset of elements that satisfy a given condition WHERE

S bl S


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Source sequence IEnumerable

Predicate TSource =>bool or (TSource,int) =>bool aa Prohibited with LINQ to SQL and Entity Framework.

Query syntax

where bool-expression

Enumerable.Where implementation

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DOO\HTXLYDOHQWWRWKHIROORZLQJ

public static IEnumerableWhere (this IEnumerablesource, Func predicate){ foreach (TSource element in source)

if (predicate (element))yield return element;


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Number of elements to take or skip int

TakeHPLWVWKHILUVWQ HOHPHQWVDQGGLVFDUGVWKHUHVWSkipGLVFDUGVWKHILUVWQHOHPHQWV

DQGHPLWVWKHUHVW7KHWZRPHWKRGVDUHXVHIXOWRJHWKHUZKHQLPSOHPHQWLQJDZHE

SDJHDOORZLQJ D XVHUWRQDYLJDWHWKURXJK DODUJH VHW RIPDWFKLQJUHFRUGV )RU LQ

VWDQFHVXSSRVHDXVHUVHDUFKHVDERRNGDWDEDVHIRUWKHWHUPPHUFXU\DQGWKHUH

DUHPDWFKHV7KHIROORZLQJUHWXUQVWKHILUVW

IQueryablequery =dataContext.Books .Where (b =>b.Title.Contains ("mercury")).OrderBy (b =>b.Title) .Take (20);

7KHQH[WTXHU\UHWXUQVERRNVWR

IQueryablequery =dataContext.Books

.Where (b =>b.Title.Contains ("mercury"))O d B (b >b Titl )


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Transforms each input element with the given lambda expression SELECT

SelectMany Transforms each input element, and then flattens and concatenates theresultant subsequences

INNER JOIN,

LEFT OUTER JOIN,

CROSS JOIN


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)LJXUH3URMHFWLQJDQREMHFWKLHUDUFK\


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Result selector TSource =>IEnumerableor (TSource,int) =>IEnumerable a

a Prohibited with LINQ to SQL

Query syntax

from identifier1 in enumerable-expression1from identifier2 in enumerable-expression2...

Enumerable implementation

public static IEnumerableSelectMany (IEnumerablesource, Func selector){ foreach (TSource element in source)


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Applies a lookup strategy to match elements from two collections, emittinga flat result set

INNER JOIN

GroupJoin As above, but emits a hierarchicalresult set INNER JOIN,

LEFT OUTER JOIN

Join and GroupJoin


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p

Join arguments

Argument Type

Outer sequence IEnumerable

Inner sequence IEnumerable

Outer key selector TOuter =>TKey

Inner key selector TInner =>TKey

Result selector (TOuter,TInner) =>TResult

GroupJoin arguments

Argument Type

+ SelectMany Flat Bad Yes Yes Yes Yes


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Select + Select Nested Bad Yes Yes Yes YesJoin Flat Good Yes - - -

GroupJoin Nested Good Yes Yes - -

GroupJoin + SelectMany Flat Good Yes Yes - -

Join

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WZRVHFWLRQV


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Input sequence IEnumerable

Key selector TSource =>TKey

5HWXUQW\SHIOrderedEnumerable

ThenBy and ThenByDescending arguments

Argument TypeInput sequence IOrderedEnumerable


Query syntax

orderby expression1 [descending][, expression2 [descending]... ]


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Overview

OrderByUHWXUQV DVRUWHGYHUVLRQRIWKHLQSXWVHTXHQFHXVLQJWKHkeySelectorH[

SUHVVLRQWRPDNHFRPSDULVRQV7KHIROORZLQJTXHU\HPLWVDVHTXHQFHRIQDPHVLQ

DOSKDEHWLFDORUGHU

IEnumerablequery =names.OrderBy (s =>s);

7KHIROORZLQJVRUWVQDPHVE\OHQJWK

IEnumerablequery =names.OrderBy (s =>s.Length);

// Result: {"Jay", "Tom", "Mary", "Dick", "Harry"};

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0DU\LFNLVLQGHWHUPLQDWHXQOHVV\RXDSSHQGDThenByRSHUDWRU
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Groups a sequence into subsequences GROUP BY

GroupBy


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GroupBy

Argument Type

Input sequence IEnumerable


Element selector (optional) TSource =>TElement

Comparer (optional) IEqualityComparer

Query syntax

group element-expression by key-expression

Overview


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Returns a concatenation of elements in each of the two sequences UNION ALL

Union Returns a concatenation of elements in each of the two sequences,l di d li t

UNION


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q ,excluding duplicates

Intersect Returns elements present in both sequences WHERE ... IN (...)

Except Returns elements present in the first, but not the second sequence EXCEPT

or

WHERE... NOT IN(...)

Concat and Union

ContactUHWXUQV DOO WKHHOHPHQWVRIWKHILUVWVHTXHQFHIROORZHGE\DOOWKHHOHPHQWV

RIWKHVHFRQGUnionGRHVWKHVDPHEXWUHPRYHVDQ\GXSOLFDWHV

int[]seq1 ={1,2,3},seq2={3,4,5};


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Converts IEnumerable to IEnumerable, discarding wrongly typed elementsCast Converts IEnumerable to IEnumerable, throwing an exception if there are any wrongly

typed elements

ToArray Converts IEnumerableto T[]

ToList Converts IEnumerableto List

ToDictionary Converts IEnumerableto Dictionary

ToLookup Converts IEnumerableto ILookup

AsEnumerable Downcasts to IEnumerable

AsQueryable Casts or converts to IQueryable

OfType and Cast

OfType DQG Cast DFFHSW D QRQJHQHULF IEnumerable FROOHFWLRQ DQG HPLW D JHQHULF


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IEnumerableVHTXHQFHWKDW\RXFDQVXEVHTXHQWO\TXHU\

ArrayList classicList =new ArrayList(); // in System.CollectionsclassicList.AddRange ( new int[]{3, 4, 5 });IEnumerablesequence1 =classicList.Cast();

CastDQG OfTypeGLIIHULQWKHLUEHKDYLRUZKHQHQFRXQWHULQJDQLQSXWHOHPHQWWKDWV

RIDQLQFRPSDWLEOHW\SH CastWKURZVDQH[FHSWLRQ OfTypeLJQRUHVWKHLQFRPSDWLEOHHOHPHQW&RQWLQXLQJWKHSUHFHGLQJH[DPSOH

DateTime offender =DateTime.Now;classicList.Add (offender);IEnumerable sequence2 =classicList.OfType(), // OK - ignores offending DateTime sequence3 =classicList.Cast(); // Throws exception

7KH UXOHV IRU HOHPHQW FRPSDWLELOLW\ H[DFWO\ IROORZ WKRVH RI &V i RSHUDWRU DQG


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Input sequence IEnumerableKey selector TSource =>TKey

Element selector (optional) TSource =>TElement

Comparer (optional) IEqualityComparer

ToDictionaryDOVR IRUFHVLPPHGLDWHH[HFXWLRQRIDVHTXHQFHZULWLQJWKHUHVXOWVWR

DJHQHULFDictionary7KH keySelectorH[SUHVVLRQ\RXSURYLGHPXVWHYDOXDWHWRD


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XQLTXH YDOXH IRU HDFK HOHPHQW LQ WKH LQSXW VHTXHQFH RWKHUZLVH DQ H[FHSWLRQ LV

WKURZQ,QFRQWUDVW ToLookupDOORZVPDQ\HOHPHQWVRIWKHVDPHNH\:HGHVFULEH

ORRNXSVLQWKHHDUOLHUVHFWLRQ-RLQLQJZLWKORRNXSVRQSDJH

AsEnumerable and AsQueryable

AsEnumerable XSFDVWVD VHTXHQFHWR IEnumerable IRUFLQJ WKH FRPSLOHUWRELQG

VXEVHTXHQWTXHU\RSHUDWRUVWRPHWKRGVLQEnumerableLQVWHDGRI Queryable)RUDQ

H[DPSOHVHHWKHVHFWLRQ&RPELQLQJ,QWHUSUHWHGDQG/RFDO4XHULHVRQSDJH

LQ&KDSWHU

AsQueryableGRZQFDVWVDVHTXHQFHWR IQueryableLILWLPSOHPHQWVWKDWLQWHUIDFH

2WKHUZLVHLWLQVWDQWLDWHVDQIQueryableZUDSSHURYHUWKHORFDOTXHU\

Equivalent to First/FirstOrDefault, butthrows an exception if thereis more than one match

ElementAt, ElementAtOrDefault Returns the element at thespecified position

Exception thrown

DefaultIfEmpty Returns null ordefault(TSource) ifthe sequence has noelements

OUTER JOIN

0HWKRGVHQGLQJLQ2UHIDXOWUHWXUQ default(TSource)UDWKHU WKDQWKURZLQJDQ

H[FHSWLRQ LI WKH LQSXW VHTXHQFH LV HPSW\ RU LI QR HOHPHQWV PDWFK WKH VXSSOLHGSUHGLFDWH

default(TSource)LV nullIRUUHIHUHQFHW\SHHOHPHQWVRUEODQNXVXDOO\]HURIRU

YDOXHW\SHHOHPHQWV

First, Last, and Single

Argument Type


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Argument Type


Predicate (optional) TSource =>bool

7KHIROORZLQJH[DPSOHGHPRQVWUDWHVFirstDQGLast

int[]numbers ={1, 2, 3, 4, 5 };int first =numbers.First(); // 1int last =numbers.Last(); // 5int firstEven =numbers.First (n =>n %2 ==0); // 2int lastEven =numbers.Last (n =>n %2 ==0); // 4

7KHIROORZLQJGHPRQVWUDWHVFirstYHUVXVFirstOrDefault

i t fi tBi E b Fi t ( > >10) // E ti


Index of element to return int

ElementAtSLFNVWKHQWKHOHPHQWIURPWKHVHTXHQFH

int[]numbers ={1, 2, 3, 4, 5 };

int third =numbers.ElementAt (2); // 3int tenthError =numbers.ElementAt (9); // Exceptionint tenth =numbers.ElementAtOrDefault (9); // 0

Enumerable.ElementAtLV ZULWWHQVXFKWKDWLIWKHLQSXWVHTXHQFHKDSSHQVWRLPSOH

PHQWIListLWFDOOV IListVLQGH[HU2WKHUZLVHLWHQXPHUDWHV Q WLPHVDQG

WKHQUHWXUQVWKHQH[WHOHPHQWElementAtLVQRWVXSSRUWHGLQ/,14WR64/RU()

DefaultIfEmpty


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DefaultIfEmptyFRQYHUWVHPSW\VHTXHQFHVWRQXOO default()7KLVLVXVHGLQZULWLQJ

IODWRXWHUMRLQVVHHWKHHDUOLHUVHFWLRQV2XWHUMRLQVZLWK6HOHFW0DQ\RQSDJH

DQG)ODWRXWHUMRLQVRQSDJH

Aggregation Methods

IEnumerablezscalar

Method Description SQL equivalents

Count, LongCount Returns the number of elements in the input sequence,optionally satisfying a predicate

COUNT (...)

Mi M R t th ll t l t l t i th MIN ( ) MAX ( )


Result selector (optional) TSource =>TResult

MinDQGMaxUHWXUQWKHVPDOOHVWRUODUJHVWHOHPHQWIURPDVHTXHQFH

int[]numbers ={28, 32, 14 };int smallest =numbers.Min(); // 14;


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int smallest numbers.Min(); // 14;int largest =numbers.Max(); // 32;

,I\RXLQFOXGHDselectorH[SUHVVLRQHDFKHOHPHQWLVILUVWSURMHFWHG

int smallest =numbers.Max (n =>n %10); // 8;

$ selector H[SUHVVLRQ LV PDQGDWRU\ LI WKH LWHPV WKHPVHOYHV DUH QRW LQWULQVLFDOO\

FRPSDUDEOHLQRWKHUZRUGVLIWKH\GRQRWLPSOHPHQWIComparable

Purchase runtimeError =dataContext.Purchases.Min (); // Errordecimal?lowestPrice =dataContext.Purchases.Min (p =>p.Price); // OK

$ selectorH[SUHVVLRQGHWHUPLQHVQRWRQO\KRZHOHPHQWVDUHFRPSDUHGEXWDOVR

WKHILQDOUHVXOW,QWKHSUHFHGLQJH[DPSOHWKHILQDOUHVXOWLVDGHFLPDOYDOXHQRWD

SXUFKDVHREMHFW7RJHWWKHFKHDSHVWSXUFKDVH\RXQHHGDVXETXHU\


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Returns true if the input sequence contains the given element WHERE ... IN (...)

Any Returns true if any elements satisfy the given predicate WHERE ... IN (...)All Returns true if all elements satisfy the given predicate WHERE (...)

SequenceEqual Returns true if the second sequence has identical elements to the inputsequence

Contains and Any

7KHContainsPHWKRG DFFHSWVDQDUJXPHQWRIW\SH TSource AnyDFFHSWVDQRSWLRQDO

SUHGLFDWH

ContainsUHWXUQVtrueLIWKHJLYHQHOHPHQWLVSUHVHQW

bool hasAThree =new int[]{2, 3, 4 }.Contains (3); // true;

AnyUHWXUQVtrueLIWKHJLYHQH[SUHVVLRQLVWUXHIRUDWOHDVWRQHHOHPHQW:HFDQUHZULWH

WKHSUHFHGLQJTXHU\ZLWKAnyDVIROORZV

bool hasAThree =new int[]{2 3 4 }Any (n =>n ==3); // true;


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bool hasAThree =new int[]{2, 3, 4 }.Any (n =>n ==3); // true;

AnyFDQGRHYHU\WKLQJWKDWContainsFDQGRDQGPRUH

bool hasABigNumber =new int[]{2, 3, 4 }.Any (n =>n >10); // false;

&DOOLQJ AnyZLWKRXWDSUHGLFDWHUHWXUQVtrueLIWKHVHTXHQFHKDVRQHRUPRUHHOH

PHQWV+HUHVDQRWKHUZD\WRZULWHWKHSUHFHGLQJTXHU\

bool hasABigNumber =new int[]{2, 3, 4 }.Where (n =>n >10).Any();

AnyLVSDUWLFXODUO\XVHIXOLQVXETXHULHVDQGLVXVHGRIWHQZKHQTXHU\LQJGDWDEDVHV

IRUH[DPSOH

from c in dataContext.Customerswhere c.Purchases.Any (p =>p.Price >1000)

l

Creates an empty sequence

Repeat Creates a sequence of repeating elementsRange Creates a sequence of integers

Empty RepeatDQG Range DUHVWDWLFQRQH[WHQVLRQPHWKRGVWKDWPDQXIDFWXUHVLPSOH

ORFDOVHTXHQFHV

EmptyEmptyPDQXIDFWXUHVDQHPSW\VHTXHQFHDQGUHTXLUHVMXVWDW\SHDUJXPHQW

foreach (string s in Enumerable.Empty()) Console.Write (s); //

,QFRQMXQFWLRQZLWKWKH??RSHUDWRU EmptyGRHVWKHUHYHUVHRIDefaultIfEmpty)RU

H[DPSOH VXSSRVH ZH KDYH D MDJJHG DUUD\ RI LQWHJHUV DQG ZH ZDQW WR JHW DOO WKH

LQWHJHUVLQWRDVLQJOHIODWOLVW7KHIROORZLQJSelectManyTXHU\IDLOVLIDQ\RIWKHLQQHUDUUD\VLVQXOO


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int[][]numbers ={ new int[]{1, 2, 3 }, new int[]{4, 5, 6 }, null // this null makes the query below fail.

};

IEnumerableflat =numbers.SelectMany (innerArray =>innerArray);

EmptyLQFRQMXQFWLRQZLWK??IL[HVWKHSUREOHP

IEnumerableflat =numbers.SelectMany (innerArray =>innerArray ??Enumerable.Empty ());


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LastNode {get; } XContainer

IEnumerable Nodes() XContainer*

DescendantNodes() XContainer*

DescendantNodesAndSelf() XElement*

XElement Element (XName) XContainer

IEnumerable Elements() XContainer*

Elements (XName) XContainer*

Descendants() XContainer* Descendants (XName) XContainer*

DescendantsAndSelf() XElement*

DescendantsAndSelf (XName) XElement*

bool HasElements {get; } XElement

)XQFWLRQVPDUNHGZLWKDQDVWHULVNLQWKHWKLUGFROXPQRIWKLVDQGRWKHUWDEOHVDOVRRSHUDWHRQVHTXHQFHVRIWKHVDPHW\SH)RU

LINQtoXML


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)LQVWDQFH \RX FDQ FDOONodes RQ HLWKHU DQXContainer RU D VHTXHQFH RIXContainer REMHFWV 7KLV LV SRVVLEOH EHFDXVH RI H[WHQVLRQPHWKRGVGHILQHGLQSystem.Xml.LinqWKHVXSSOHPHQWDU\TXHU\RSHUDWRUVZHWDONHGDERXWLQWKHRYHUYLHZ

FirstNode, LastNode, and Nodes

FirstNodeDQG LastNodeJLYH\RXGLUHFWDFFHVVWRWKHILUVWRUODVWFKLOGQRGHNodes

UHWXUQVDOOFKLOGUHQDVDVHTXHQFH$OOWKUHHIXQFWLRQVFRQVLGHURQO\GLUHFWGHVFHQG

DQWV)RUH[DPSOH


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Ancestors (XName) XNode* AncestorsAndSelf() XElement*

AncestorsAndSelf (XName) XElement*

,IxLVDQXElementWKHIROORZLQJDOZD\VSULQWVtrue

foreach (XNode child in x.Nodes())

Console.WriteLine (child.Parent ==x);

7KHVDPHLVQRWWKHFDVHKRZHYHULIxLVDQXDocument XDocumentLVSHFXOLDULWFDQ

KDYHFKLOGUHQ EXWFDQQHYHUEHDQ\RQHVSDUHQW7RDFFHVVWKHXDocument\RXLQVWHDG


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KDYHFKLOGUHQ EXWFDQQHYHUEHDQ\RQHVSDUHQW7RDFFHVVWKHXDocument\RXLQVWHDG

XVHWKHDocumentSURSHUW\WKLVZRUNVRQDQ\REMHFWLQWKH;20WUHH

AncestorsUHWXUQVDVHTXHQFHZKRVHILUVWHOHPHQWLVParentDQGZKRVHQH[WHOHPHQW

LVParent.ParentDQGVRRQXQWLOWKHURRWHOHPHQW


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LastAttribute {get; } XElement

IEnumerable Attributes() XElement

Attributes (XName name) XElement

,QDGGLWLRQXAttributeGHILQHV PreviousAttribute DQGNextAttributeSURSHUWLHVDV

ZHOODVParent

7KHAttributesPHWKRGWKDWDFFHSWVDQDPHUHWXUQVDVHTXHQFHZLWKHLWKHU]HURRU

RQHHOHPHQWDQHOHPHQWFDQQRWKDYHGXSOLFDWHDWWULEXWHQDPHVLQ;0/

, XAttribute

Value {get; set } XElement, XAttribute

7KHSetValuePHWKRG UHSODFHVDQHOHPHQWRUDWWULEXWHVFRQWHQWZLWKDVLPSOHYDOXH6HWWLQJWKHValueSURSHUW\GRHVWKHVDPHEXWDFFHSWVVWULQJGDWDRQO\:HGHVFULEH

ERWKRIWKHVHIXQFWLRQVLQGHWDLOODWHULQWKLVFKDSWHUVHHWKHVHFWLRQ:RUNLQJZLWK

9DOXHVRQSDJH

$QHIIHFWRIFDOOLQJSetValueRUUHDVVLJQLQJ ValueLVWKDWLWUHSODFHVDOOFKLOGQRGHV

XElement settings =new XElement ("settings",

new XElement ("timeout", 30) );settings.SetValue ("blah");Console.WriteLine (settings.ToString()); // blah

Updating Child Nodes and Attributes

Category Members Works onAdd Add (params object[]content) XContainer

AddFirst (params object[]content) XContainer


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AddFirst (params object[]content) XContainer

Remove RemoveNodes() XContainer

RemoveAttributes() XElement

RemoveAll() XElement

Update ReplaceNodes (params object[]content) XContainer

ReplaceAttributes (params object[]content) XElement

ReplaceAll (params object[]content XElement

SetElementValue (XName name, object value) XElement

SetAttributeValue (XName name, object value) XElement

, XAttribute*

ReplaceWith (params object[]content) XNode

7KHPHWKRGV AddBeforeSelf AddAfterSelf RemoveDQG ReplaceWith GRQWRSHUDWH

RQWKHQRGHVFKLOGUHQ,QVWHDGWKH\RSHUDWHRQWKHFROOHFWLRQLQZKLFKWKHQRGH

LWVHOILVLQ7KLVUHTXLUHVWKDWWKHQRGHKDYHDSDUHQWHOHPHQWRWKHUZLVHDQH[FHS

WLRQLVWKURZQAddBeforeSelfDQG AddAfterSelfDUHXVHIXOIRULQVHUWLQJDQRGHLQWR

DQDUELWUDU\SRVLWLRQ

XElement items =new XElement ("items", new XElement ("one"), new XElement ("three")

);items.FirstNode.AddAfterSelf (new XElement ("two"));

+HUHVWKHUHVXOW

LINQtoXML


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,QVHUWLQJLQWRDQDUELWUDU\SRVLWLRQZLWKLQDORQJVHTXHQFHRIHOHPHQWVLVDFWXDOO\

TXLWHHIILFLHQWEHFDXVHQRGHVDUHVWRUHGLQWHUQDOO\LQDOLQNHGOLVW

7KHRemovePHWKRGUHPRYHVWKHFXUUHQWQRGHIURPLWVSDUHQWReplaceWithGRHVWKH

VDPHDQGWKHQLQVHUWVVRPHRWKHUFRQWHQWDWWKHVDPHSRVLWLRQ)RULQVWDQFH

XElement items =XElement.Parse ("");items.FirstNode.ReplaceWith (new XComment ("One was here"));

+HUHVWKHUHVXOW


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http://www.w3.org/2001/xmlschema-instancehttp://www.w3.org/2001/xmlschema-instance


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x

ReadString Text x x

ReadElementString Element x x

MoreXML


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ReadElementString Element x x

ReadElementContentAsXXX Element x x

ReadInnerXml Element x x

ReadOuterXml Element x x

ReadStartElement Element x

ReadEndElement Element x

ReadSubtree Element x x


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...> customer

customer

x:customer

7KHIROORZLQJFRGHZRUNVZLWKWKHILUVWWZRFDVHV

reader.ReadStartElement ("customer");

7KHIROORZLQJLVUHTXLUHGWRKDQGOHWKHWKLUGFDVH

reader.ReadStartElement ("x:customer");

7KHVHFRQG V\VWHPZRUNVWKURXJKWZR QDPHVSDFHDZDUHSURSHUWLHV NamespaceURI

DQG L lN 7KHVH SURSHUWLHV WDNH LQWR DFFRXQW SUHIL[HV DQG GHIDXOW QDPHVSDFHV


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DQGLocalName7KHVHSURSHUWLHVWDNHLQWRDFFRXQWSUHIL[HVDQGGHIDXOWQDPHVSDFHV

GHILQHGE\SDUHQWHOHPHQWV3UHIL[HVDUHDXWRPDWLFDOO\H[SDQGHG7KLVPHDQVWKDWNamespaceURIDOZD\VUHIOHFWVWKHVHPDQWLFDOO\FRUUHFWQDPHVSDFHIRUWKHFXUUHQWHO

HPHQWDQGLocalNameLVDOZD\VIUHHRISUHIL[HV

:KHQ\RXSDVVWZRQDPHDUJXPHQWVLQWRDPHWKRGVXFKDV ReadStartElement\RXUH

XVLQJWKLVVDPHV\VWHP)RUH[DPSOHFRQVLGHUWKHIROORZLQJ;0/

dd


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http://oreilly.com/


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http://www.w3.org/tr/xpath20/http://www.w3.org/tr/xpath20/


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Children

// Recursively children

. Current node (usually implied)

.. Parent node

* Wildcard

@ Attribute

[] Filter: Namespace separator

7RILQGWKHcustomersQRGH

XmlNode node =doc.SelectSingleNode ("customers");

7KH / V\PERO TXHULHV FKLOG QRGHV 7R VHOHFW WKH customer QRGHV


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7KH/V\PEROTXHULHVFKLOGQRGHV7RVHOHFWWKHcustomerQRGHV

XmlNode node =doc.SelectSingleNode ("customers/customer");

7KH // RSHUDWRULQFOXGHV DOOFKLOG QRGHVUHJDUGOHVV RIQHVWLQJ OHYHO 7R VHOHFW DOO

lastnameQRGHV

XmlNodeList nodes =doc.SelectNodes ("//lastname");


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Prevents further I/O When you later need to read/write the stream

StreamReader,StreamWriter Flushes the reader/writer andcloses the underlying stream When you want to keep the underlying stream open (youmust instead call Flush on a StreamWriter whenyoure done)

IDbConnection Releases a database connectionand clears the connection string

If you need to re-Open it, you should call Close insteadof Dispose

DataContext(LINQ to SQL)

Prevents further use When you might have lazily evaluated queries connectedto that context

MemoryStreamV DisposePHWKRG GLVDEOHVRQO\WKHREMHFWLWGRHVQWSHUIRUPDQ\FULW

LFDO FOHDQXS EHFDXVH DMemoryStream KROGV QR XQPDQDJHG KDQGOHV RU RWKHU VXFK

UHVRXUFHV

7KHWKLUGFDWHJRU\LQFOXGHVWKHIROORZLQJFODVVHV WebClient StringReader String

WriterDQG BackgroundWorkerLQ System.ComponentModel7KHVHW\SHVDUHGLVSRVD

EOH XQGHU WKH GXUHVV RI WKHLU EDVH FODVV UDWKHU WKDQ WKURXJK D JHQXLQH QHHG WR SHUIRUP


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EOHXQGHUWKHGXUHVVRIWKHLUEDVHFODVVUDWKHUWKDQWKURXJKDJHQXLQHQHHGWRSHUIRUPHVVHQWLDOFOHDQXS,I\RXKDSSHQWRLQVWDQWLDWHDQGZRUNZLWKVXFKDQREMHFWHQWLUHO\

LQ RQH PHWKRGZUDSSLQJ LWLQ Dusing EORFN DGGV OLWWOHLQFRQYHQLHQFH %XWLI WKH

REMHFWLVORQJHUODVWLQJNHHSLQJWUDFNRIZKHQLWVQRORQJHUXVHGVRWKDW\RXFDQ

GLVSRVH RI LW DGGV XQQHFHVVDU\ FRPSOH[LW\ ,Q VXFK FDVHV \RX FDQ VLPSO\ LJQRUH

REMHFWGLVSRVDO


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Reading public abstract bool CanRead {get; }

public abstract int Read (byte[]buffer, int offset, int count) public virtual int ReadByte();

Writing public abstract bool CanWrite {get; }

public abstract void Write (byte[]buffer, int offset, int count);

public virtual void WriteByte (byte value);

Seeking public abstract bool CanSeek {get; }

public abstract long Position {get; set; }

public abstract void SetLength (long value);

public abstract long Length {get; }

public abstract long Seek (long offset SeekOrigin origin);

StreamsandI/O


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Reading one char public virtual int Peek(); // Cast the result to a char

public virtual int Read(); // Cast the result to a char

Reading manychars

public virtual int Read (char[]buffer, int index, int count);

public virtual int ReadBlock (char[]buffer, int index, int count);

public virtual string ReadLine();

public virtual string ReadToEnd();

Closing public virtual void Close();

public void Dispose(); // Same as Close

Other public static readonly TextReader Null;

public static TextReader Synchronized (TextReader reader);

StreamsandI/O


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Writing one char public virtual void Write (char value);

Writing many chars public virtual void Write (string value);

public virtual void Write (char[]buffer, int index, int count);

public virtual void Write (string format, params object[]arg); public virtual void WriteLine (string value);

Closing and flushing public virtual void Close();

public void Dispose(); // Same as Close

public virtual void Flush();

Formatting and

encoding

public virtual IFormatProvider FormatProvider {get; }

public virtual string NewLine {get; set; }

public abstract Encoding Encoding {get; }

Other public static readonly TextWriter Null;

public static TextWriter Synchronized (TextWriter writer);

WriteLineVLPSO\DSSHQGVWKHJLYHQWH[WZLWK&5/)


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chars 0 to 31 and "|

Path.GetInvalidFileNameChars() chars 0 to 31 and "|:*?\/

Temporary files:

Path.GetTempPath() \Temp

Path.GetRandomFileName() d2dwuzjf.dnpPath.GetTempFileName() \Temp\tmp14B.tmp

CombineLVSDUWLFXODUO\XVHIXOLWDOORZV\RXWRFRPELQHDGLUHFWRU\DQGILOHQDPH

RUWZR GLUHFWRULHVZLWKRXW ILUVW KDYLQJ WR FKHFN ZKHWKHU D WUDLOLQJ EDFNVODVK LV

S

treamsandI/O


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AssemblyRoaming

AssemblyMachine

GetMachineStoreForAssembly

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HYHU -XVW H[SRVH D SXEOLF PHWKRG LQ RQH RI WKH DVVHPEOLHV WKDW LQVWDQWLDWHV DQG

UHWXUQVDQIsolatedStorageFileStreamREMHFW$Q\DVVHPEO\FDQDFFHVVDQ\LVRODWHGVWRUH LI JLYHQ DQIsolatedStorageFile REMHFWLVRODWLRQ UHVWULFWLRQV DUH LPSRVHG

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Reading and Writing Isolated Storage

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Local user \Users\\AppData\Local\IsolatedStorage

Roaming user \Users\\AppData\Roaming\IsolatedStorageMachine \ProgramData\IsolatedStorage

)RU:LQGRZV;3

Scope Location

Local user \Documents and Settings\\Local Settings\Application Data\Isolated-Storage

Roaming user \Documents and Settings\\Application Data\IsolatedStorage

Machine \Documents and Settings\All Users\Application Data\IsolatedStorage

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Enumerating Isolated Storage

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using (IsolatedStorageFile f =IsolatedStorageFile.GetUserStoreForDomain()){

using (var s =new IsolatedStorageFileStream ("f1.x",FileMode.Create,f)) s.WriteByte (123);

using (var s =new IsolatedStorageFileStream ("f2.x",FileMode.Create,f)) s.WriteByte (123);

StreamsandI/O


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DNS Domain Name Service Converts between domain names (e.g., ebay.com) and IP addresses(e.g., 199.54.213.2)

FTP File Transfer Protocol Internet-based protocol for sending and receiving files

HTTP Hypertext Transfer Protocol Retrieves web pages and runs web services

IIS Internet Information Services Microsofts web server software

IP Internet Protocol Network-layer protocol below TCP and UDP

LAN Local Area Network Most LANs use Internet-based protocols such as TCP/IPPOP Post Office Protocol Retrieves Internet mail

SMTP Simple Mail Transfer Protocol Sends Internet mail

TCP Transmission and ControlProtocol

Transport-layer Internet protocol on top of which most higher-layerservices are built

UDP Universal Datagram Protocol Transport-layer Internet protocol used for low-overhead services such

as VoIP

UNC Universal Naming Convention \\computer\sharename\filename

URI Uniform Resource Identifier Ubiquitous resource naming system (e.g., http://www.amazon.comor mailto:[email protected])

URL Uniform Resource Locator Technical meaning (fading from use): subset of URI; popular meaning:synonym of URI

Addresses and Ports

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Networkin

g
http://ebay.com/http://www.amazon.com/mailto:mailto:[email protected]:mailto:[email protected]://www.amazon.com/http://ebay.com/


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http://www.ietf.org/http://www.ietf.org/http://www.ietf.org/


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http://www.albahari.com/nutshell/


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http://0.0.0.0/


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http://0.0.0.0/


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http://ebay.com/


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Client connects... +OKHello there. Welcome message

USER j +OK P d q i d
http://0.0.0.0/http://0.0.0.0/


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USER joe +OK Password required.

PASS password +OK Logged in.

LIST +OK

1 1876

2 5412

3 845

.

Lists the ID and file size of each message on the server

RETR 1 +OK 1876 octets

Content of message #1...

.

Retrieves the message with the specified ID

DELE 1 +OK Deleted. Deletes a message from the server

QUIT +OK Bye-bye.

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static string ReadLine (Stream s){ ListlineBuffer =new List(); while (true) { int b =s.ReadByte(); if (b ==10 ||b


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Level of automation *** ***** **** *

Type coupling Choice Tight Loose Loose

Version tolerance ***** *** ***** *****

Preserves object references Choice Yes No ChoiceCan serialize nonpublic fields Yes Yes No Yes

Suitability for interoperable messaging ***** ** **** ****

Flexibility in reading/writing XML files ** - **** *****

Compact output ** **** ** **

Performance *** **** * to *** ***

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, GetName Returns the fully qualified name or anAssemblyName object

Assembly Names on page 655

CodeBase, Location Location of the assembly file Resolving and Loading Assem-blies on page 671

Load LoadFrom LoadFile Manually loads an assembly into the Resolving and Loading Assem


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Load, LoadFrom, LoadFile Manually loads an assembly into thecurrent application domain

Resolving and Loading Assem-blies on page 671

GlobalAssemblyCache Indicates whether the assembly is de-fined in the GAC

The Global AssemblyCache on page 661

GetSatelliteAssembly Locates the satellite assembly of agiven culture

Resources and Satellite Assem-blies on page 663

GetType, GetTypes Returns a type, or all types, defined inthe assembly

Reflecting and ActivatingTypes on page 682

EntryPoint Returns the applications entrymethod, as a MethodInfo

Reflecting and Invoking Mem-bers on page 688

GetModules,ManifestModule

Returns all modules, or the main mod-ule, of an assembly

Reflecting Assemblieson page 700

GetCustomAttributes Returns the assemblys attributes Working with Attrib-utes on page 701

Strong Names and Assembly Signing

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http://www.ksoftware.net/


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Event GetEvent Event name EventInfo

Constructor GetConstructor ConstructorInfo

Finalizer GetMethod "Finalize" MethodInfo

Operator GetMethod "op_"+ operator name MethodInfo

Nested type GetNestedType Type name Type

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MethodInfo m =typeof (Walnut).GetMethod ("Crack");Console.WriteLine (m); // Void Crack()Console.WriteLine (m.ReturnType); // System.Void

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MethodInfo method =typeof (Walnut).GetMethod ("Crack");MemberInfo member =typeof (Walnut).GetMember ("Crack") [0];

Console.Write (method ==member); // True

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C# Members Versus CLR Members

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