2 - Ngon ngu C#

NGN NG C#

C#

Ngn ng lp trnh thun hng i tng

70% Java, 10% C++, 5% Visual Basic, 15% mi

Trnh bin dch C# l mt trong nhng trnh bin dch

hiu qu nht trong dng sn phm .NET.

c im ca ngn ng C#

Khong 80 t kha

H tr lp trnh cu trc, lp trnh hng i tng, hng

thnh phn (Component oriented)

C t kha khai bo dnh cho thuc tnh (property)

Cho php to su liu trc tip bn trong m ngun (dng

tool m ngun m NDoc pht sinh ra su liu)

H tr khi nim interface (tng t java)

C ch t ng dn rc (tng t java)

Truyn tham s kiu: in(), out, ref

Cu trc chng trnh C#

Hello World

01 using System;

02

03 class Hello

04 {

05 public static void Main()

06 {

07 Console.WriteLine("Hello, World");

08 }

09 }

Namespace

Namespace cung cp cho cch t chc quan h gia cc lp v cc kiu khc.

Namespace l cch m .NET trnh n vic cc tn lp, tn bin, tn hm trng tn gia cc lp.

namespace CustomerPhoneBookApp

{

using System;

public struct Subscriber

{ // Code for struct here... }

}

Namespace

T kho using gip gim vic phi gnhng namespace trc cc hm hnh vihoc thuc tnh

using Wrox.ProCSharp;

Ta c th gn b danh cho namespace

C php :

using alias = NamespaceName;

V d

bin dch tng Class, c th s dng tp tin csc.exe trong ca s Command Prompt vi khai bo nh sau:

D:\csc CSharp\ Hello.cs

01 /* Chng trnh c bn ca C#*/

02

03 class Hello

04 {

05 static void Main(string[] args)

06 {

07 System.Console.WriteLine("Hello C Sharp");

08 System.Console.ReadLine();

09 }

10 }

Console.WriteLine

public static void Main() {

int a = 1509; int b = 744; int c = a + b;

Console.Write("The sum of ");

Console.Write(a);

Console.Write(" and ") ;

Console.Write(b);

Console.Write(" equals ");

Console.WriteLine(c);

Console.WriteLine("The sum of " + a + " and " +

b + "="+c) ;

Console.WriteLine(" {0} + {1} = {2}", a, b, c);

Console.ReadLine();

}

Console.WriteLine

Console.WriteLine("Standard Numeric Format

Specifiers");

Console.WriteLine(

"(C) Currency: . . . . . . . . {0:C}\n" +

"(D) Decimal:. . . . . . . . . {0:D}\n" +

"(E) Scientific: . . . . . . . {1:E}\n" +

"(F) Fixed point:. . . . . . . {1:F}\n" +

"(G) General:. . . . . . . . . {0:G}\n" +

" (default):. . . . . . . . {0}

(default = 'G')\n" +

"(N) Number: . . . . . . . . . {0:N}\n" +

"(P) Percent:. . . . . . . . . {1:P}\n" +

"(R) Round-trip: . . . . . . . {1:R}\n" +

"(X) Hexadecimal:. . . . . . . {0:X}\n",

-123, -123.45f);

Console.WriteLine

Console.WriteLine

Console.WriteLine("Standard DateTime Format Specifiers");

Console.WriteLine(

"(d) Short date: . . . . . . . {0:d}\n" +

"(D) Long date:. . . . . . . . {0:D}\n" +

"(t) Short time: . . . . . . . {0:t}\n" +

"(T) Long time:. . . . . . . . {0:T}\n" +

"(f) Full date/short time: . . {0:f}\n" +

"(F) Full date/long time:. . . {0:F}\n" +

"(g) General date/short time:. {0:g}\n" +

"(G) General date/long time: . {0:G}\n" +

" (default):. . . . . . . . {0} (default

= 'G')\n" +

"(M) Month:. . . . . . . . . . {0:M}\n" +

"(R) RFC1123:. . . . . . . . . {0:R}\n" +

"(s) Sortable: . . . . . . . . {0:s}\n" +

"(u) Universal sortable: . . . {0:u} (invariant)\n"

+

"(U) Universal sortable: . . . {0:U}\n" +

"(Y) Year: . . . . . . . . . . {0:Y}\n",

thisDate);

Console.WriteLine

Console.ReadLine()

public static string ReadLine ()

Convert.ToBoolean();

Convert.ToByte();

Convert.ToInt16();

Byte.Parse();

Int64.Parse();

Double.Parse()

Kiu d liu trong C#

Kiu d liu nh sn

Kiu C# S byte Kiu .NET M t

byte 1 Byte S nguyn dng khng du t 0-255

char 2 Char K t Unicode

bool 1 Boolean Gi tr logic true/ false

sbyte 1 Sbyte S nguyn c du ( t -128 n 127)

short 2 Int16 S nguyn c du gi tr t -32768 n 32767

ushort 2 UInt16 S nguyn khng du 0 65.535

Kiu d liu nh sn


int 4 Int32 S nguyn c du - 2.147.483.647 n 2.147.483.647

uint 4 Uint32 S nguyn khng du 0 4.294.967.295

float 4 Single Kiu du chm ng, 3,4E-38 n 3,4E+38, vi 7 ch s c ngha..

double 8 Double Kiu du chm ng c chnh xc gp i1,7E-308 n 1,7E+308vi 15,16 ch s c ngha.

Kiu d liu nh sn


decimal 8 Decimal C chnh xc n 28 con sdng trong tnh ton ti chnh

phi c hu t m hay Mtheo sau gi tr

long 8 Int64 Kiu s nguyn c du-9.223.370.036.854.775.808

n9.223.372.036.854.775.807

ulong 8 Uint64 S nguyn khng du t 0 n 0xffffffffffffffff

Kiu d liu nh sn

Console.WriteLine("sbyte:{0} to {1} ",sbyte.MinValue,sbyte.MaxValue);

Console.WriteLine("byte:{0} to {1}", byte.MinValue, byte.MaxValue);

Console.WriteLine("short:{0} to {1}", short.MinValue, short.MaxValue);

Console.WriteLine("ushort:{0} to {1}", ushort.MinValue,

ushort.MaxValue);

Console.WriteLine("int:{0} to {1}", int.MinValue, int.MaxValue);

Console.WriteLine("long:{0} to {1}", long.MinValue, long.MaxValue);

Console.WriteLine("decimal:{0} to {1}", decimal.MinValue,

decimal.MaxValue);

Console.ReadLine();

07/03/2013 Lp Trnh mi trng Windows 20

Kiu d liu nh sn

Chuyn i kiu d liu

Chuyn i d liu l cho php mt biu thc ca kiu d liu ny c xem xt nh mt kiu d liu khc.

Chuyn i c th: n ngm nh (implicit) hay tng minh (explicit),

v d,

int a = 123;

long b = a;

// t int sang long (implicit)

int c = (int) b;

// t long sang int (explicit)

Enum(eration) kiu tp hp

enum Days {Sat, Sun, Mon, Tue, Wed, Thu, Fri};

Days d = Days.Mon;

switch (d) {

case Days.Tue:

case Days.Wed:

}

R hn cch dng hng truyn thng ca Cconst int Sat = 1;

const int Fri = 6;

Value type vs reference type

55

105A

B ?

?A

B

105

55

?

?A

B

105

struct

struct : value type (class : reference type)

Dng cho cc i tng nh nhPoint, Rectangle, Color,

public struct MyPoint {

public int x, y;

public MyPoint(int p1, int p2) {

x = p1;

y = p2;

}

}

Box v Unbox

i qua li gia value type v reference type.

Box: value => reference (object).

Thng dng trong cc hm, cu trc d liu s dng tham s l kiu object tng qut.

int i = 123;

object o = i; // implicit boxing

object o = (object) i; // explicit boxing

int j = (int) o; // unboxing

Box v Unbox

Cc nhm ton t trong C#

Nhm ton t Ton t

Ton hc + - * / %

Logic & | ^ ! ~ && || true false

Ghp chui +

Tng, gim ++, --

Dch bit >

Quan h == != < > =

Gn = += -= *= /= %= &= |= ^= =

Ch s [ ]

p kiu ( )

Indirection v Address * -> [ ] &

Th t u tin ca ton tNhm ton t Ton t

Primary {x} x.y f(x) a[x] x++ x--

Unary + - ! ~ ++x -x (T)x

Nhn * / %

Cng + -

Dch bit >

Quan h < > = is

Bng == !=

Logic trn bit AND &

XOR ^

OR |

iu kin AND &&

iu kin OR ||

iu kin ?:

Assignment = *= /= %= += -= = &= ^= |=

Kiu mng

1 mng l 1 tp cc im d liu (ca cng kiu c s), c truy cp dng 1 s ch mc

Cc mng trong C# pht sinh t lp c s System.Array

Mng c th cha bt c kiu no m C# nh ngha, bao gm cc mng i tng, cc giao din, hoc cc cu trc

Mng c th 1 chiu hay nhiu chiu, v c khai bo bng du ngoc vung ([ ] ) t sau kiu d liu ca mng

VD:

int [] a;

Kiu mng

Khai bo bin mng c hai cch nh sau

1) Khai bo v khi to mng

int[] yourarr=new int[ptu];

2) Khai bo sau khi to mng

int[] myarr;

myarr=new int[ptu];

Khai bo mng vi s phn t cho trc v khi to gi tr cho cc phn t ca mng:

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

float[] arr = { 3.14f, 2.17f, 100 };

float[] arr = new float [3] { 3.14f, 2.17f, 100 };

Kiu mng

arr.length: s phn t ca mng

Khai bo mng 2 chiu:

int [,] Mang2chieu;

Mang2chieu = new int[3,4]

Khai bo mng ca mng:

int [][] M=new int[2][];

M[0]=new int[4];

M[1]= new int[30];

Kiu string

Kiu string l 1 kiu d liu tham chiu trong C#

System.String cung cp cc hm tin ch nh: Concat(), CompareTo(), Copy(), Insert(), ToUpper(), ToLower(), Length, Replace(),

Cc ton t == v != c nh ngha so snh cc gi tr ca cc i tng chui, ch khng phi l b nh m chng tham chiu n

Ton t & l cch tc k thay cho Concat()

C th truy cp cc k t ring l ca 1 chui dng ton t ch mc ([ ])

Kiu pointer

Kiu pointer c khai bo vi du * ngay sau loi d liu v trc tn bin cng vi t kho unsafe.

Bin dch ng dng C# c s dng kiu d liu pointer:

D:\csc pointer.cs /unsafe

Kiu pointer

Khng ging nh hai kiu d liu value v reference, kiu pointer khng chu s kim sot ca garbage collector

Garbage collector khng dng cho kiu d liu ny do chng khng bit d liu m con tr tr n

V vy, pointer khng cho php tham chiu n reference hay mt struct c cha cc kiu references v kiu tham chiu ca pointer thuc loi kiu khng qun l (unmanaged-type).

Tham s

Tham tr: tham s c gi tr khng thay i trc v sau khi thc hin phng thc

Tham bin: tham s c gi tr thay i trc v sau khi thc hin phng thc, c th i sau cc t kha: ref, out, params

- ref: tham s i theo sau phi khi to trc khi truyn vo phng thc

- out: tham s khng cn khi to trc khi truyn vo phng thc

- params: tham s nhn i s m s lng i s l bin, t kho ny thng s dng tham s l mng.

T Kha ref

void MyMethod()

{

int num1 = 7, num2 = 9;

Swap(ref num1, ref num2);

// num1 = 9, num2 = 7

}

void Swap(ref int x, ref int y)

{

int temp = x; x = y; y = temp;

}

Keyword out

void MyMethod()

{

int num1 = 7, num2;

Subtraction(num1, out num2);

// num1 = 7, num2 = 5

}

void Subtraction(int x, out int y)

{

y = x - 2;

// y must be assigned a value

}

uninitialised

Keyword params

void MyMethod()

{

int sum = Addition(1, 2, 3); // sum = 6

}

int Addition(params int[] integers)

{

int result = 0;

for (int i = 0; i < integers.Length; i++)

result += integers[i];

return result;

}

Keyword var

Thay v s dng khai bo bin thng thng ta c th sdng t kha var khai bo bin kiu ngm nh. Mtbin c khai bo bng t kha ny vn c kiu c th, chkhc l kiu ny trnh bin dch xc nh t gi tr c gn.

V d:

var int_variable = 6; // int_variable is compiled as an int

var string_variable = "Mony"; // string_variable is compiled as a string

var int_array = new[] { 0, 1, 2 }; // int_array is compiled as int[]

Anonymous Type

To ra 1 kiu mi trong lc chy (khng tn ti cp source code). Kiu mi bao gm mt tp nhng thuc tnh read-only.

V d:

var obj1 = new { Name = "Mony Hamza", SSN ="12345678" };

// Display the contents:

Console.WriteLine("Name: {0}\nSSN: {1}", obj1.Name,obj1.SSN);

Console.ReadLine();

Pht biu chn

Pht biu chn (selection statement) trong C# bao gm cc

pht biu (if, ifelse, switchcase).

Pht biu if

if (expression)

statement

if (expression)

{

statement1

statement1

}

Pht biu ifelseif (expression)

statement1else

statement2

Pht biu switchcase l pht biu iu khin nhiu chn la bng cch truyn iu khin n pht biu case bn trong.

switch (expression)

{

case constant-expression:

statement

jump-statement

[default:

statement

jump-statement]

}

Pht biu switchcase

Pht biu lp

Pht biu vng lp trong C# bao gm do, for, foreach, while.

Vng lp do

do

statement

while (expression);

Vng lp while

while (expression)

statement

Vng lp for

for ([initializers]; [expression]; [iterators])

statement

Vng lp foreach in

foreach (type identifier in expression)

statement

Vng lp foreach lp li mt nhm pht biu cho mi phn ttrong mng hay tp i tng.

Pht biu dng duyt qua tt c cc phn t trong mnghay tp i tng v thc thi mt tp lnh

Pht biu lp

Pht biu nhy

Pht biu nhy s c s dng khi chng trnh mun chuyn i iu khin.

Pht biu nhy: break, continue, default, goto, return

Statement Example

Local variable declaration static void Main() { int a; int b = 2, c = 3; a = 1; Console.WriteLine(a + b + c);

}

Local constant declaration static void Main() { const float pi = 3.1415927f; const int r = 25; Console.WriteLine(pi * r * r);

}

Expression statement static void Main() { int i; i = 123;

Console.WriteLine(i); i++; // tng i ln 1Console.WriteLine(i);

}

Tm tt

Statement Example

if statement static void Main(string[] args) { if (args.Length == 0) {

Console.WriteLine("No arguments"); } else { Console.WriteLine("One or more arguments"); }

}

switch statement static void Main(string[] args) { int n = args.Length; switch (n) {

case 0: Console.WriteLine("No arguments"); break;

case 1: Console.WriteLine("One argument"); break;

default: Console.WriteLine("{0} arguments", n); break;

} }

Tm tt

Statement Example

while statement static void Main(string[] args) { int i = 0; while (i < args.Length) {

Console.WriteLine(args[i]); i++; }

}

do statement static void Main() { string s; do {

s = Console.ReadLine(); if (s != null) Console.WriteLine(s);

} while (s != null); }

for statement static void Main(string[] args) { for (int i = 0; i < args.Length; i++)

Console.WriteLine(args[i]);}


Tm tt

Statement Example

foreach statement static void Main(string[] args) { foreach (string s in args) Console.WriteLine(s);

}

break statement static void Main() { while (true) {

string s = Console.ReadLine(); if (s == null) break; Console.WriteLine(s);

} }

continue statement static void Main(string[] args) { for (int i = 0; i < args.Length; i++) {

if (args[i].StartsWith("/")) continue; Console.WriteLine(args[i]);

} } 07/03/2013 Lp Trnh mi trng Windows 49

Tm tt

Statement Example

goto statement static void Main(string[] args) { int i = 0; goto check;

loop: Console.WriteLine(args[i++]); check: if (i < args.Length) goto loop;

}

return statement static int Add(int a, int b) { return a + b; } static void Main() {

Console.WriteLine(Add(1, 2)); return;

}

checked and unchecked statements

static void Main() {int i = int.MaxValue; checked { Console.WriteLine(i + 1);// Exception } unchecked { Console.WriteLine(i + 1);// Overflow }

}

Tm tt

Statement Example

lock statement class Account { decimal balance; public void Withdraw(decimal amount) {

lock (this) { if (amount > balance)

throw new Exception("Insufficient funds"); balance -= amount;

} }

}

using statement static void Main() { using (TextWriter w = File.CreateText("test.txt")) {

w.WriteLine("Line one"); w.WriteLine("Line two"); w.WriteLine("Line three");

} }


Tm tt

Statement Example

throw and trystatements

static double Divide(double x, double y) { if (y == 0) throw new DivideByZeroException(); return x / y;

} static void Main(string[] args) {

try { if (args.Length != 2)

throw new Exception("Two numbers required"); double x = double.Parse(args[0]); double y = double.Parse(args[1]);Console.WriteLine(Divide(x, y));

} catch (Exception e) { Console.WriteLine(e.Message);

} }

Tm tt

OOP in C#

Khai bo lp

[Thuc tnh] [B t truy cp]

class [: Lp c s]

{

}

Thuc tnh truy cp

Thuc tnh Gii hn truy vp

public Khng hn ch

private Ch trong lp (mc nh)

protected Trong lp v lp con(lp dn xut)

internal Trong chng trnh

protected internal

Trong chng trnh v trong lp con

V d

01 using System;

02 public class ThoiGian

03 {

04 public void ThoiGianHienHanh()

05 {

06 Console.WriteLine("Hien thi thoi gian

hien hanh");

07 }

08 // Cc bin thnh vin

09 int Nam;

10 int Thang;

11 int Ngay;

12 int Gio;

13 int Phut;

14 int Giay;

15 }

16 public class Tester

17 {

18 static void Main()

19 {

20 ThoiGian t = new ThoiGian();

21 t.ThoiGianHienHanh();

22 }

23 }

V d

Khi to gi tr cho thuc tnh

01 public class ThoiGian

02 {

03 public void ThoiGianHienHanh()

04 {

05 System.DateTime now = System.DateTime.Now;

06 System.Console.WriteLine("\n Hien tai: \t

{0}/{1}/{2}{3}:{4}:{5}",

07 now.Day, now.Month, now.Year, now.Hour,

now.Minute, now.Second);

08 System.Console.WriteLine(" Thoi Gian:\t

{0}/{1}/{2}{3}:{4}:{5}",

09 Ngay, Thang, Nam, Gio, Phut, Giay);

10 }

11 public ThoiGian( System.DateTime dt)

12 {

13 Nam = dt.Year;Thang = dt.Month;Ngay = dt.Day;

14 Gio = dt.Hour;Phut = dt.Minute;

15 Giay = dt.Second;

16 }


17 public ThoiGian(int Year, int Month, int Date,

int Hour, int Minute)

18 {

19 Nam = Year;Thang = Month;Ngay = Date;

20 Gio = Hour;Phut = Minute;

21 }

22 private int Nam;

23 private int Thang;

24 private int Ngay;

25 private int Gio;

26 private int Phut;

27 private int Giay = 30 ; // bin c khi to.

28 }



30 {


32 {

33 System.DateTime currentTime =

System.DateTime.Now;

34 ThoiGian t1 = new ThoiGian( currentTime );

35 t1.ThoiGianHienHanh();

36 ThoiGian t2 = new ThoiGian(2001,7,3,10,5);

37 t2.ThoiGianHienHanh();

38 }

39 }

Phng thc khi to


Hm to mc nh: ging C++

Hm to c i s: tng t C++

public class MyClass{

public MyClass() // zero-parameter constructor {

// construction code }public MyClass(int number) // another overload{

// construction code }

}

Phng thc khi to sao chp

C# khng cung cp phng thc khi to sao chp

public ThoiGian( ThoiGian tg)

{

Nam = tg.Nam;

Thang = tg.Thang;

Ngay = tg.Ngay;

Gio = tg.Gio;

Phut = tg.Phut;

Giay = tg.Giay;

}

Object Initializer

Tnh nng ny gip ta gim thiu s di dng khi khai bo mi mt i tng. Thay v dng cch nh gi tr member thng qua instance ca i tng, ta c th nh trc tip ngay khi va khai bo i tng

V d:

public class Person

{

public string Name { get; set; }

public int Age { get; set; }

}

public class Program

{

static void Main(string[] args)

{

var person = new Person() {Name = John", Age = 25};

}

}

Named Arguments v Optional Parameters

Optional parameters: Mt tham s c khai bo l ty chn bng cch t mt gi tr cho n:

V d:

public MyClass(int x, int y = 5, int z = 7)

{

.....

}

MyClass myClass = new MyClass(1, 2, 3); // gi constructor ca lp MyClass

MyClass myClass = new MyClass(1, 2); // thiu tham s z

MyClass myClass = new MyClass(1); // thiu tham s y v z

Named and optional arguments: C# khng cho php khng cho php trng cc tham s gia v d MyClass(1, , 3). Nu mun b trng cc tham s gia, mi tham s cn phi gn vi mt ci tn.

V d:

MyClass myClass = new MyClass(1, z: 3); // passing z by name

MyClass myClass = new MyClass(x: 1, z: 3);

hay

MyClass myClass = new MyClass(z: 3, x: 1);

Named Arguments v Optional Parameters

Phng thc hy b

C# cung cp c ch thu dn (garbage collection) v do vy khng cn phi khaibo tng minh cc phng thc hy.

Phng thc Finalize s c gi bi c ch thu dn khi i tng b hy.

Phng thc kt thc ch gii phng cc ti nguyn m i tng nm gi, v khng tham chiu n cc i tng khc

Phng thc hy b

~Class1()

{

// Thc hin mt s cng vic

}

Class1.Finalize()

{

// Thc hin mt s cng vic

base.Finalize();

}

Hm hy

class MyClass : IDisposable

{

public void Dispose()

{

// implementation

}

}

Hm hy

Lp s thc thi giao din System.IDisposable, tc l thc thi

phng thc IDisposable.Dispose().

Khng bit trc c khi no mt Destructor c gi.

C th ch ng gi thu dn rc bng cch gi phng thc

System.GC.Collect().

System.GC l mt lp c s .NET m t b thu gom rc v

phng thc Collect() dng gi b thu gom rc.

Con tr this

T kha this dng tham chiu n th hin hin hnh ca mt i tng

public void SetYear( int Nam)

{

this.Nam = Nam;

}

Tham chiu this ny c xem l con tr n n tt cc phng thc khng c thuc tnh tnh trong mt lp

Thnh vin static

Thnh vin tnh c xem nh mt phn ca lp.

C th truy cp n thnh vin tnh ca mt lpthng qua tn lp

C# khng cho php truy cp n cc phng thctnh v cc bin thnh vin tnh thng qua mt thhin.

Khng c friend

Phng thc tnh hot ng t nhiu ging nhphng thc ton cc

Partial Classes v Parial Methods

C# Cho php ta dng t kha patial phn chia lp thnh nhiu phn c th cha trn nhiu file.

01 using System;

02

03 partial class Person

04 {

05 public void Walk()

06 {

07 Console.WriteLine("Person is Walking");

08 }

09 }


11 {

12 public void Swim()

13 {

14 Console.WriteLine("Person is Swimming");

15 }

16 }

SVN



17 class Program

18 {


20 {

21 Person person = new Person();

22 person.Walk();

23 person.Swim();

24 }

25 }


Ta cng c th s dng t kha partial khai bo method nhng ta khng th xy dng method c hai ni ca partial class01 using System;

02


04 {

05 partial void Sing();

06 }


08 {

09 partial void Sing()

10 {

11 Console.WriteLine("Person is Singing");

12 }

13 public void MethodInvoker()

14 {

15 Sing();

16 }

17 }

Khi dng partial, ta khng th dng chung vi cc t kha public,private, protected, virual, abstract, override Do nu mun gipartial method th ta phi thng qua mt method khc. Trong trnghp trn l MethodInvoker().

18 class Program

19 {


21 {


23 person.MethodInvoker();

24 }

25 }


Thuc tnh (property)

Thuc tnh cho php to ra cc field read-only, write-only.

Thuc tnh cho php to ra cc field o vi bn ngoi

class Student {

protected DateTime _Birthday;

public int Age {

get {

return DateTime.Today().Year _Birthday.Year;

}

}

}

Console.Writeline(Age: {0}, chau.Age);

Thuc tnh (property)

Cho php filter cc gi tr c ghi vo field m khng phi

dng c ch hm set_xxx nh C++.

Bn ngoi c th dng nh field (dng trong biu thc)class Student {

protected DateTime _Birthday;

public int Birthday {

get {

return _Birthday;

}

set {

if ()

throw new

_Birthday = value;

}

}

}

chau.Birthday = new DateTime(2007,09,23);

Console.Writeline(Birthday: {0}, chau.Birthday);

Thuc tnh (property)

protected string foreName;//foreName l attribute ca mt lp

public string ForeName //ForeName l mt Property

{

get

{

return foreName;

}

set

{

if (value.Length > 20)

// code here to take error recovery action

// (eg. throw an exception)

else

foreName = value;

}

}

Thuc tnh (property)

Nu cu lnh Property ch c on lnh get -> thuc tnh ch c (Read Only)

Nu cu lnh Property ch c on lnh set -> thuc tnh ch ghi (Write Only)

Thuc tnh c v ghi

Cho php gn (set) gi tr vo thuc tnh hay ly (get) gi tr rat thuc tnh.

public int liA{

get{

return LiA;}set{

LiA = value; // value l t kha}

}

Thuc tnh ch c

Nu mun thuc tnh ch c, ch s dng phngthc get

public int liA

{

get

{

return LiA;

}

}

01 using System;

02 public class BankAccount

03 {

04 protected string ID;

05 protected string Owner;

06 protected decimal _Balance;

07 public BankAccount(string ID, string Owner)

08 {

09 this.ID = ID;

10 this.Owner = Owner;

11 this._Balance = 0;

12 }

13 public void Deposit(decimal Amount)

14 {

15 _Balance += Amount;

16 }

17 public void Withdraw(decimal Amount)

18 {

19 _Balance -= Amount; // what if Amount > Balance?

20 }

21 public decimal Balance

22 {

23 get

24 {

25 return _Balance;

26 }

27 }

28 };

Thuc tnh ch c

Read-only property

Fields

Thuc tnh ch c

29 class Program

30 {


32 {

33 BankAccount myAcct = new BankAccount("100120023003",

"Nguyen Van An");

34 myAcct.Deposit(1000);

35 myAcct.Withdraw(100);

36 Console.WriteLine("Balance: {0}", myAcct.Balance);

37 //myAcct.Balance=10000;

38 Console.ReadLine();

39 }

40 }

Thuc tnh ch c

Auto-Implemented Properties

Khi khng cn ci t g c bit cho get v set ca property, Auto-Implemented Properties lm cho vic khai bo property ngn gn hn.

V d:

class Employee

{

public int ID{ get; private set; } // read-only

public string FirstName { get; set; }

public int LastName { get; set; }

}

Collection Initializers

n gin ha vic b sung cc phn t ca danh sch thay v dng phng thc Add

V d:

public class Person

{

string _Name;

List _Intersets = new List();

public string Name {

get { return _Name; }

set { _Name =value; } }

public List Interests {

get { return _Intersets; }

}

}

Collection Initializers

Thay v vit:

List PersonList = new List();

Person p1 = new Person();

p1.Name = "Mony Hamza";

p1.Interests.Add("Reading");

p1.Interests.Add("Running");

PersonList.Add(p1);

Person p2 = new Person();

p2.Name = "John Luke";

p2.Interests.Add("Swimming");

PersonList.Add(p2);

Ta c th vit

var PersonList = new List{

new Person{ Name = "Mony Hamza", Interests = { "Reading", "Running" } },

new Person { Name = "John Luke", Interests = { "Swimming"}

};

Indexer

Cho php to ra cc thuc tnh ging nh array (nhng cch ci t bn trong khng nht thit dng array). Lu l ch mc khng nht thit phi l integer.

C th c nhiu ch mc

vd: Marks[string SubjectID, string SemesterID]

class Student {

protected string StudentID;

protected Database MarkDB;

public double Marks[string SubjectID] {

get {

return MarkDB.GetMark(StudentID,SubjectID);

}

set {

MarDB.UpdateMark(StudentID,value);

}

}

}

Console.Writeline(Physic mark: {0},chau.Marks[physic]);

Chng hm (overload)

Khng chp nhn hai phng thc ch khcnhau v kiu tr v.

Khng chp nhn hai phng thc ch khcnhau v c tnh ca mt thng s ang ckhai bo nh ref hay out.

S k tha

1 class ch c th k tha t 1 class c s

1 class c th k tha t nhiu Interface

T kha sealed c dng trong trng hpkhai bo class m khng cho php class khck tha.

n tha k

class MyDerivedClass : MyBaseClass

{

// functions and data members here

}

public class Window

{

// Hm khi dng ly hai s nguyn ch n v tr ca ca s trn consolepublic Window( int top, int left)

{

this.top = top;

this.left = left;

}

public void DrawWindow() // m phng v ca s

{

Console.WriteLine(Drawing Window at {0}, {1}, top, left);}

// C hai bin thnh vin private do hai bin ny s khngthy bn trong lp dn xut.

private int top;

private int left;

}

n tha k

public class ListBox: Window

{

// Khi dng c tham spublic ListBox(int top, int left,string theContents) : base(top, left)

//gi khi dng ca lp c s{

mListBoxContents = theContents;

}

// To mt phin bn mi cho phng thc DrawWindow// v trong lp dn xut mun thay i hnh vi thc hin// bn trong phng thc nypublic new void DrawWindow()

{

base.DrawWindow();

Console.WriteLine( ListBox write: {0}, mListBoxContents);}

// bin thnh vin privateprivate string mListBoxContents;

}

n tha k

public class Tester

{

public static void Main()

{

// to i tng cho lp c sWindow w = new Window(5, 10);

w.DrawWindow();

// to i tng cho lp dn xutListBox lb = new ListBox( 20, 10, Hello world!);lb.DrawWindow();

}

}

n tha k

a hnh

to mt phng thc h tnh a hnh: khai bo kha virtual trong phng thc ca lp c s

nh ngha li cc hm virtual, hm tngng lp dn xut phi c t kha Override

Phng thc Override

class MyBaseClass{

public virtual string VirtualMethod(){

return "This method is virtual and defined in MyBaseClass";}

}class MyDerivedClass : MyBaseClass{

public override string VirtualMethod(){

return "This method is an override defined in MyDerivedClass";}

}

Phng thc Override

Lp Windowpublic virtual void DrawWindow() // m phng v ca s

{

Console.WriteLine(Drawing Window at {0}, {1}, top, left);}

Lp Listboxpublic override void DrawWindow()

{

base.DrawWindow();

Console.WriteLine( ListBox write: {0}, mListBoxContents);}

Gi cc hm ca lp c s

C php : base.()class CustomerAccount{

public virtual decimal CalculatePrice(){

// implementation}

} class GoldAccount : CustomerAccount{

public override decimal CalculatePrice(){

return base.CalculatePrice() * 0.9M;}

}

V d

Window[] winArray = new Window[3];

winArray[0] = new Window( 1, 2 );

winArray[1] = new ListBox( 3, 4, List box is array);winArray[2] = new Button( 5, 6 );

for( int i = 0; i < 3 ; i++)

{

winArray[i].DrawWindow();

}

Lp c s tru tng

abstract class Building

{

public abstract decimal CalculateHeatingCost();

// abstract method

}

Mt lp abstract khng c th hin v mt phng thc abstract khng c thc thi m phi c overriden trong bt k lp tha hng khng abstract n

Nu mt lp c phng thc abstract th n cng l lp abstract

Mt phng thc abstract s t ng c khai bo virtual

Abstract class

public abstract class BankAccount {

public abstract bool IsSufficientFund(decimal Amount);

public abstract void AddInterest();

}

Khng th new mt abstract class

Ch c lp abstract mi c th cha abstract method

Lp c lp (sealed class)

Mt lp c lp th khng cho php cc lp dnxut t n

khai bo mt lp c lp dng t khasealed

Extension MethodsTnh nng ny cho php ta thm method vo mt lp c xy dng sn m khng lm nh hng n cu trc ca lp.

//Lp b nim phong, khng th k tha

sealed class Person

{

public string Name { get; set; }

}

static class Utility

{

//Extension method thm vo lp Person

static public void ExMethod(this Person person)

{

person.Name = John";

Console.WriteLine("Name: " + person.Name);

}

}

Extension Methods

class Program

{


{

//To instance ca lp Person

var person = new Person();

//Gi Extension Method

person.ExMethod();

}

}

Lp Object

Phng thc Chc nng

Equal( ) So snh bng nhau gia hai i tng

GetHashCode( ) Cho php nhng i tng cung cp ring nhng hm bm cho s dng tp hp.

GetType( ) Cung cp kiu ca i tng

ToString( ) Cung cp chui th hin ca i tng

Finalize( ) Dn dp cc ti nguyn

MemberwiseClone( ) To mt bn sao t i tng.

01 using System;

02 public class SomeClass

03 {

04 public SomeClass(int val)

05 {

06 value = val;

07 }

08 public override string ToString()

09 {

10 return value.ToString();

11 }

12 private int value;

13 }

Lp Object


15 {


17 {

18 int i = 5;

19 Console.WriteLine("The value of i is: {0}",

i.ToString());

20 SomeClass s = new SomeClass(7);

21 Console.WriteLine("The value of s is {0}",

s.ToString());

22 Console.WriteLine("The value of 5 is {0}",

5.ToString());

23 }

24 }

Lp Object

Lp trong lp

01 using System;

02 class Nguoi

03 {

04 public class Date

05 {

06 private int ngay;

07 private int thang;

08 public Date() { ngay = 1; thang = 1; }

09 public void Xuat() { Console.WriteLine(ngay + "/" +

thang); }

10 }

11 private string ten;

12 private string ho;

13 private Date ns;

14 public Nguoi() { ten = "An"; ho = "Nguyen Van"; ns = new

Date(); }

15 public void Xuat()

16 {

17 ns.Xuat(); Console.WriteLine(ho + " " + ten);

18 }

19 }

Lp trong lp

20 class Progarm

21 {

22


24 {

25 Nguoi a = new Nguoi();

26 a.Xuat();

27 Nguoi.Date ns = new Nguoi.Date();

28 ns.Xuat();

29 }

30 }

public class Fraction

{

public Fraction( int numerator, int denominator)

{

this.numerator = numerator;

this.denominator = denominator;

}

public override string ToString()

{

StringBuilder s = new StringBuilder();

s.AppendFormat({0}/{1},numerator, denominator);return s.ToString();

}

internal class FractionArtist

{.}private int numerator;

private int denominator;

}

Lp trong lp

internal class FractionArtist

{

public void Draw( Fraction f)

{

Console.WriteLine(Drawing the numerator {0}, f.numerator);

Console.WriteLine(Drawing the denominator {0}, f.denominator);

}

}

Lp trong lp

public class Tester

{

static void Main()

{

Fraction f1 = new Fraction( 3, 4);

Console.WriteLine(f1: {0}, f1.ToString());Fraction.FractionArtist fa = new

Fraction.FractionArtist();

fa.Draw( f1 );

}

}

Lp trong lp

Overload Operator

public static Fraction operator + ( Fraction lhs, Fraction rhs)

firstFraction + secondFraction

Fraction.operator+(firstFraction, secondFraction)

np chng ton t (+) th nn cung cp mt phng thcAdd() cng lm cng chc nng l cng hai i tng

Overload Operator

Overload == th phi overload !=

Overload > th phi overload = th phi overload

Overload Operator

Biu tng Tn phng thc thay th

+ Add

- Subtract

* Multiply

/ Divide

== Equals

> Compare

Phng thc Equals

public override bool Equals( object o )

pubic override bool Equals( object o)

{

if ( !(o is Phanso) )

{

return false;

}

return this == (Phanso) o;

}

Ton t chuyn i

int myInt = 5;

long myLong;

myLong = myInt; // ngm nh

myInt = (int) myLong; // tng minh

01 using System;

02 public class Phanso

03 {

04 public Phanso(int ts, int ms)

05 {

06 this.ts = ts;

07 this.ms = ms;

08 }

09 public Phanso(int wholeNumber)

10 {

11 ts = wholeNumber;

12 ms = 1;

13 }

14 public static implicit operator Phanso(int theInt)

15 {

16 return new Phanso(theInt);

17 }

Ton t chuyn i

18 public static explicit operator int(Phanso thePhanso)

19 {

20 return thePhanso.ts / thePhanso.ms;

21 }

22 public static bool operator ==(Phanso lhs, Phanso rhs)

23 {

24 if (lhs.ts == rhs.ts && lhs.ms == rhs.ms)

25 {

26 return true;

27 }

28 return false;

29 }

30 public static bool operator !=(Phanso lhs, Phanso rhs)

31 {

32 return !(lhs == rhs);

33 }

Ton t chuyn i

34 public override bool Equals(object o)

35 {

36 if (!(o is Phanso))

37 {

38 return false;

39 }

40 return this == (Phanso)o;

41 }

42 public static Phanso operator +(Phanso lhs, Phanso

rhs)

43 {

44 if (lhs.ms == rhs.ms)

45 {

46 return new Phanso(lhs.ts + rhs.ts, lhs.ms);

47 }

48 int firstProduct = lhs.ts * rhs.ms;

49 int secondProduct = rhs.ts * lhs.ms;

50 return new Phanso(firstProduct + secondProduct,

lhs.ms * rhs.ms);

51 }

Ton t chuyn i


53 {

54 string s = ts.ToString() + "/" + ms.ToString();

55 return s;

56 }

57 private int ts;

58 private int ms;

59 }

Ton t chuyn i


61 {


63 {

64 Phanso f1 = new Phanso(3, 4);

65 Console.WriteLine("f1:{0}", f1.ToString());


67 Console.WriteLine("f2:{0}", f2.ToString());

68 Phanso f3 = f1 + f2;

69 Console.WriteLine("f1 + f2 = f3:{0}", f3.ToString());

70 Phanso f4 = f3 + 5;

71 Console.WriteLine("f4 = f3 + 5:{0}", f4.ToString());

72 Phanso f6 = 5+ f3 ;

73 Console.WriteLine("f6 = 5 + f3:{0}", f6.ToString());


75 if (f5 == f2)

76 {

77 Console.WriteLine("f5:{0}==f2:{1}",f5.ToString(),

f2.ToString());

78 }

79 }

80 }

Ton t chuyn i


Ton t chuyn i

Interface(giao din)

Interface l rng buc, giao c m bo cho cc lp

hay cc cu trc s thc hin mt iu g .

Khi mt lp thc thi mt giao din, th lp ny bo cho cc

thnh phn client bit rng lp ny c h tr cc

phng thc, thuc tnh, s kin v cc ch mc

khai bo trong giao din.

Giao din chnh l phn c t (khng bao hm phn ci t

c th ni dung) ca 1 lp.

Mt lp i tng c th a ra cng lc nhiu giao din

cc chng trnh bn ngoi truy xut

Interface(giao din)

Ging m khng ging abstract class! (kh phn bit)

Interface ch c method hoc property, KHNG c field

(Abstract c th c tt c)

Tt c member ca interface KHNG c php ci t, ch l

khai bo (Abstract class c th c mt s phng thc c ci

t)

Tn cc interface nn bt u bng I

V d: ICollection, ISortable

Interface(giao din)

C php nh ngha mt giao din:

[thuc tnh] [b t truy cp] interface [: danh sch c s]

{

}

Interface(giao din)

Mt giao din th khng c Constructor

Mt giao din th khng cho php cha cc phng thc np chng.

N cng khng cho php khai bo nhng b t trn cc thnh phn trong khi nh ngha mt giao din.

Cc thnh phn bn trong mt giao din lun lun l public v khng th khai bo virtual hay static.

Interface(giao din)

Khi mt class khai bo l implement mt interface, n phiimplement tt c method hoc thuc tnh ca interface

Nu hai interface c trng tn method hoc property, trongclass phi ch r (explicit interface)

V d: IMovable v IEngine u c thuc tnh MaxSpeed

class ToyotaCar: Car, IMovable, IEngine {

public IMovable.MaxSpeed {

}

public IEngine.MaxSpeed {

}

}

V d

To mt giao din nhm m t nhng phng thc v thuc tnh ca mt lp cn thit

lu tr

truy cp

t mt c s d liu hay cc thnh phn lu tr d liu khc nh l mt tp tin

interface IStorable

{

void Read();

void Write(object);

}

public class Document : IStorable

{

public void Read()

{

....

}

public void Write()

{

....

}

}

Interface(giao din)

Thc thi nhiu giao din:

public class Document : IStorable, Icompressible

M rng giao dininterface ILoggedCompressible : ICompressible

{

void LogSavedBytes();

}

Kt hp cc giao din:interface IStorableCompressible : IStoreable, ILoggedCompressible

{

void LogOriginalSize();

}

Interface(giao din)

Ton t is

is

Ton t as

as

Interface vs Abstract

Abstract: phn nh tt c c im (k c cu trc ni ti) chung nht ca mt tp i tng no .

Interface: phn nh mt phn c im (bn ngoi) ca mt loi i tng. Hai i tng v mt bn cht c th rt khc nhau nhng vn c th c chung mt phn c im no ging nhau.

V d: xe hi Toyota v hc sinh u c tnh cht chung l di chuyn c

interface IMovable

{

public 3DPoint Position { get; set; }

public double MaxSpeed { get; set; }

public MoveTo(3DPoint newPosition);

}

Interface vs Abstract

Mt class ch c tha k t mt lp c s

Nhng c php implement (ci t, hin thc ha) nhiu loi interface khc nhau.

public class ToyotaCar: Car, IMovable, IUsePower

{

}

public class Student: People, IMovable, IBreathable

{

}

X l li

Chng trnh no cng c kh nng gp phi cc tnh hung khng mong mun

ngi dng nhp d liu khng hp l

a cng b y

file cn m b kha

i s cho hm khng hp l

X l nh th no?

Mt chng trnh khng quan trng c th dng li

Chng trnh iu khin khng lu? iu khin my bay?

X l li truyn thng

X l li truyn thng thng l mi hm li thng bo trng thi thnh cng/tht bi qua mt m li

bin ton cc (chng hn errno)

gi tr tr v

int remove ( const char * filename );

tham s ph l tham chiu

double MyDivide(double numerator,

double denominator, int& status);

exception

Exception ngoi l l c ch thng bo v x l ligii quyt c cc vn k trn

Tch c phn x l li ra khi phn thut tonchnh

cho php 1 hm thng bo v nhiu loi ngoi l Khng phi hm no cng phi x l li nu c mt s

hm gi thnh chui, ngoi l ch ln c x l timt hm l

khng th b qua ngoi l, nu khng, chng trnhs kt thc

Tm li, c ch ngoi l mm do hn kiu x l litruyn thng

X l ngoi l

C# cho php x l nhng li v cc iu kin khng bnh thng vi nhng ngoi l.

Ngoi l l mt i tng ng gi nhng thng tin v s c ca mt chng trnh khng bnh thng

Khi mt chng trnh gp mt tnh hung ngoi l to mt ngoi l. Khi mt ngoi l c to ra, vic thc thi ca cc chc nng hin hnh s b treo cho n khi no vic x l ngoi l tng ng c tm thy

Mt trnh x l ngoi l l mt khi lnh chng trnh c thit k x l cc ngoi l m chng trnh pht sinh

X l ngoi l

nu mt ngoi l c bt v c x l:

chng trnh c th sa cha c vn v tip tc thc hin hot ng

in ra nhng thng ip c ngha

Pht biu throw

Pht biu throw dng pht ra tn hiu ca s cbt thng trong khi chng trnh thc thi vi cphp:

throw [expression];

01 using System;

02 public class ThrowTest

03 {


05 {

06 string s = null;

07 if (s == null)

08 {

09 throw (new ArgumentNullException());

10 }

11 Console.Write("The string s is null");

12 // not executed

13 }

14 }

Pht biu throw

01 using System;

02 public class Test

03 {


05 {

06 Console.WriteLine("Enter Main....");

07 Test t = new Test();

08 t.Func1();

09 Console.WriteLine("Exit Main...");

10 }

11 public void Func1()

12 {

13 Console.WriteLine("Enter Func1...");

14 Func2();

15 Console.WriteLine("Exit Func1...");

16 }

17 public void Func2()

18 {

19 Console.WriteLine("Enter Func2...");

20 throw new System.Exception();

21 Console.WriteLine("Exit Func2...");

22 }

23 }

Pht biu throw

Pht biu throw

Pht biu try catch

Trong C#, mt trnh x l ngoi l hay mt on chng trnh x l cc ngoi l c gi l mt

khi catch v c to ra vi t kha catch..

V d: cu lnh throw c thc thi bn trong khi try, v mt khi catch c s

dng cng b rng mt li c x l

public void Func2()

{

Console.WriteLine(Enter Func2...);try

{

Console.WriteLine(Entering try block...);throw new System.Exception();

Console.WriteLine(Exiting try block...);}

catch

{

Console.WriteLine(Exception caught and handled.);}

Console.WriteLine(Exit Func2...);}

Pht biu try catch

public void Func1()

{

Console.WriteLine(Enter Func1...);try

{

Console.WriteLine(Entering try block...);Func2();

Console.WriteLine(Exiting try block...);}

catch

{

Console.WriteLine(Exception caught and handled.);}

Console.WriteLine(Exit Func1...);}

Pht biu try catch

Pht biu try catch

V d

01 using System;

02 class Test

03 {


05 {

06 Test t = new Test();

07 t.TestFunc();

08 }

09 public double DoDivide(double a, double b)

10 {

11 if (b == 0)

12 throw new System.DivideByZeroException();

13 if (a == 0)

14 throw new System.ArithmeticException();

15 return a / b;

16 }

17 public void TestFunc()

18 {

19 try

20 {

21 double a = 5;

22 double b = 0;

23 Console.WriteLine("{0} / {1} = {2}", a, b,

DoDivide(a, b));

24 }

25 catch (System.DivideByZeroException)

26 {

27 Console.WriteLine("DivideByZeroException caught!");

28 }

29 catch (System.ArithmeticException)

30 {

31 Console.WriteLine("ArithmeticException caught!");

32 }

33 catch

34 {

35 Console.WriteLine("Unknown exception caught");

36 }

37 }

38 }

V d

Cu lnh finally

try

try-block

catch

catch-block

finally

finally-block

on chng trnh bn trong khi finally c m bo

thc thi m khng quan tm n vic khi no th mt

ngoi l c pht sinh

Cu lnh finally

1. Dng thc thi bc vo khi try.

2. Nu khng c li xut hin,

- tin hnh mt cch bnh thng xuyn sut khi try, v khi n cui khi try, dng thc thi s nhy n khi finally ( bc 5),

- nu mt li xut hin trong khi try,thc thi s nhy n khi catch ( bc tip theo)

3. Trng thi li c x l trong khi catch

4. vo cui ca khi catch , vic thc thi c chuyn mt cch t ng n khi finally

5. khi finally c thc thi

To ring ngoi l

phi c dn xut t System.ApplicationException

Dynamic Binding

Vi dynamic binding, khi nhn c mt i tng, chng ta khng cn phi quan tm kiu ca i tng . Mi trng thc thi s quyt nh phng thc hay php ton no s p dng cho i tng no. iu ny to to s linh hot v n gin khi code

V d:

01 using System;

02 class Person

03 {

04 public string Name { get; set; }


06 {

07 Console.WriteLine("Person is swimming");

08 }

09 }

10 class Duck

11 {

12 public string Weight { get; set; }


14 {

15 Console.WriteLine("The Duck is swimming");

16 }

17 }

18 class Program

19 {

20 //Hm c paramater l mt object dynamic

21 static void InvokeSwim(dynamic obj)

22 {

23 obj.Swim();

24 }

Dynamic Binding

Dynamic Binding


26 {

27 //Khai bo 2 object dynamic khc nhau

28 dynamic person = new Person();

29 dynamic duck = new Duck();

30 //Truyn 2 object khc kiu vo cng 1 hm

31 InvokeSwim(person);

32 InvokeSwim(duck);

33 }

34 }

Dynamic Binding

Dynamic h tr tt cc Operator +, -, *, /

static dynamic Sum(dynamic obj1, dynamic obj2)

{

return obj1 + obj2;

}


{

Console.WriteLine(Sum(5, 10));

Console.WriteLine(Sum(5.2, 10.2));

}

Delegates

Mt i tng kiu delegate s cha cc thng tin v method m n tr ti. Nh vy delegate cng ging nh con tr hm trong C++.

V d:

01 using System;

02 delegate void MethodDelegate();

03 class Person

04 {

05 public void Hello()

06 {

07 Console.WriteLine("Hello Delegate");

08 }

09 }

Delegates

10 class Program

11 {


13 {


15 MethodDelegate helloDelegate =

new MethodDelegate(person.Hello);

16 helloDelegate(); //gi hm

17 }

18 }

Delegates01 using System;

02 delegate void FunctionToCall(ref int x);

03 class Delegate2

04 {

05 public static void Add2(ref int x)

06 {

07 x += 2;

08 }

09 public static void Add3(ref int x)

10 {

11 x += 3;

12 }


14 {

15 // Khai bo ng thi gn bng Add2

16 FunctionToCall functionDelegate = Add2;

17 functionDelegate += Add3;



Delegates20 int x = 5;

21 functionDelegate(ref x); // Gi delegate

22 Console.WriteLine("Value: {0}", x);

23 int y = 5;

24 functionDelegate = Add2;


26 functionDelegate -= Add2;

27 functionDelegate(ref y); // Gi delegate

28 Console.WriteLine("Value: {0}", y);


30 }

31 }

Gi private static method t lp khc01 using System;


03 class Person

04 {

05 public void Hello(MethodDelegate mDelegate)

06 {


08 //Gi Method c truyn vo

09 if (mDelegate != null)

10 mDelegate();

11 }

12 }

13 class Program

14 {

15 private static void priMethod()

16 {

17 Console.WriteLine("Private Method");

18 }

Gi private static method t lp khc


20 {


22

23 //Khai bo delegate tr ti privateMethod

24 MethodDelegate helloDelegate = new

MethodDelegate(priMethod);

25

26 //Truyn delegate vo method Hello nh mt i

s

27 person.Hello(helloDelegate);

28 }

29 }

30

Multicasting

Khng nhng i din cho mt method, delegate cn c kh nng tr ti nhiu method cng lc.01 using System;


03 class Person

04 {

05 public void Hello()

06 {


08 }


10 {

11 Console.WriteLine("Person is swimming");

12 }

13 }

Multicasting14 class Program

15 {


17 {


19 MethodDelegate multicastDelegate = null;

20

21 //Multicasting delegate

22 multicastDelegate += new

MethodDelegate(person.Hello);

23 multicastDelegate += new

MethodDelegate(person.Swim);

24

25 multicastDelegate();

26 }

27 }

Events

Event l cc s kin xy ra khi chy chng trnh (s kin click ca button, s kin gi tr ca comboBox thay i,). Event gip x l code lnh hot v n gin hn. Khi s dng Event th chng ta khng cn quan tm n vic khi no th t hm x l v khi event pht sinh n s t ng gi hm x l ra thc hin.

V d:

01 using System;

02 internal delegate void TextChanged();

03 class Person

04 {

05 public event TextChanged TextChanged

06 {

07 add { Console.WriteLine("Event added"); }

08 remove { Console.WriteLine("Event removed"); }

09 }

10 }

11 class Program

12 {


14 {


16 person.TextChanged += new

TextChanged(person_TextChanged);

17 person.TextChanged -= new

TextChanged(person_TextChanged);

18 }

19

20 private static void person_TextChanged()

21 {

22 Console.WriteLine("Event Called");

23 }

24 }

Events

Anonymous Method

Thay v khai bo mt event nh sau

person.TextChanged += new TextChanged(person_TextChanged);

Event tr ti method

private static void person_TextChanged()

{

Console.WriteLine("Event Called");

}

By gi vi tnh nng anonymous method, ta c th n gin ha nh sau

person.TextChanged += delegate()

{

Console.WriteLine("Event Called");

};

Lambda Expressions

Lambda Expression c dng vit nhng phng thc anonymous ngn gn dng to ra cc delegate

V d:

01 using System;

02 public delegate int MyDelegate(int n);

03 class LambdaExpresion

04 {


06 {

07 // Anonymous method that returns the argument

multiplied by 10:

08 MyDelegate Obj1 = new MyDelegate(delegate(int

n) { return n * 10; });

09 // Display the result:

10 Console.WriteLine("The value using an

anonymous method is: {0}", Obj1(5));

11 // Using lambda expression to do the

same job:

12 MyDelegate Obj2 = (int n) => n * 10;

13 // Display the result:

14 Console.WriteLine("The value using a

lambda expression is: {0}", Obj2(5));


16 }

17 }

Lambda Expressions

Mi trng .NET cung cp nhng giao din chun cho vic lit k, so snh, v to cc tp hp.

Giao din tp hp

IEnumerable Khi mt lp ci t giao din ny, i tng thuc lp

c th dng trong cu lnh foreach.

ICollection Thc thi bi tt c cc tp hp cung cp phng thc

CopyTo() cng nh cc thuc tnh Count,

ISReadOnly, ISSynchronized, v SyncRoot.

IComparer So snh gia hai i tng lu gi trong tp hp

sp xp cc i tng trong tp hp.

IList S dng bi nhng tp hp mng c ch mc

IDictionary Dng trong cc tp hp da trn key va value

IDictionaryEnumerator Cho php lit k dng cu lnh foreach qua tp hp

h tr IDictionary.

Interface ny ch c mt phng thc duynht l GetEnumerator(), cng vic caphng thc l tr v mt s thc thi c bitca IEnumerator.

Mc ch ca interface IEnumerable l chophp chng ta c th s dng t kha foreachtrn i tng ca class ci t interface ny.

Interface IEnumerable

Interface IEnumerator bao gm 2 phng thc quan trng l

MoveNext, Reset v thuc tnh Current.

Thuc tnh Current tr v phn t hin ti ang c duyt ti trong danh

sch.

MoveNext dng i n phn t tip theo trong danh sch (hay ni

cch khc thay i gi tr ca Property Current). Phng thc ny tr v

gi tr true nu nh vic di chuyn n i tng tip theo thnh cng, tr

v false nu tht bi (trong trng hp n cui danh sch).

Reset dng a con tr hin ti v v tr ban u. V tr ban u ny l v

tr nm ngy trc phn t u tin trong danh sch.

Interface IEnumerator

01 using System;

02 using System.Collections;

03 public class Person

04 {

05 public Person(string fName, string lName)

06 {

07 this.firstName = fName;

08 this.lastName = lName;

09 }

10 public string firstName;

11 public string lastName;

12 }

13 public class People : IEnumerable

14 {

15 private Person[] _people;

16 // Khi to

17 public People(Person[] pArray)

18 {

19 _people = new Person[pArray.Length];

20

21 for (int i = 0; i < pArray.Length; i++)

22 {

23 _people[i] = pArray[i];

24 }

25 }

V d

26 IEnumerator IEnumerable.GetEnumerator()

27 {

28 return (IEnumerator)GetEnumerator();

29 }

30 public PeopleEnum GetEnumerator()

31 {

32 return new PeopleEnum(_people);

33 }

34 }

35

36 public class PeopleEnum : IEnumerator

37 {

38 public Person[] _people;

39 int position = -1;

40 // Khi to

41 public PeopleEnum(Person[] list)

42 {

43 _people = list;

44 }

45 // Tng v tr

46 public bool MoveNext()

47 {

48 position++;

49 return (position < _people.Length);

50 }

V d

51 public void Reset()

52 {

53 position = -1;

54 }

55 object IEnumerator.Current

56 {

57 get

58 {

59 return Current;

60 }

61 }

62 public Person Current

63 {

64 get

65 {

66 try

67 {

68 return _people[position];

69 }

70 catch (IndexOutOfRangeException)

71 {

72 throw new InvalidOperationException();

73 }

74 }

75 }

76 }

V d

77 class Program

78 {


80 {

81 Person[] peopleArray = new Person[3]

82 {

83 new Person("John", "Smith"),

84 new Person("Jim", "Johnson"),

85 new Person("Sue", "Rabon"),

86 };

87 People peopleList = new People(peopleArray);

88 // lit k danh sch dng foreach

89 foreach (Person p in peopleList)

90 Console.WriteLine(p.firstName + " " + p.lastName);

91 PeopleEnum peopleEnum = peopleList.GetEnumerator();

92 peopleEnum.Reset();

93 // ly ngi u tin trong danh sch

94 peopleEnum.MoveNext();

95 Person firstPerson = peopleEnum.Current;

96 Console.WriteLine("First Person: {0} {1}",

firstPerson.firstName , firstPerson.lastName);

97 }

98 }

V d

Interface ICollection cung cp cc thuc tnh: Count, IsSynchronized, v SyncRoot. Ngoi ra ICollection cng cung cp mt phng thc CopyTo(). Thuc tnh thng c s dng l Count, thuc tnh ny tr v s thnh phn trong tp hp.

Interface ICollection

Vai tr ca IComparable l cung cp mt phng php ComparteTo() dng so snh hai i tng.

Interface IComparable

01 using System;


03 public class Employee : IComparable

04 {

05 private int empID;

06 public Employee(int empID)

07 {

08 this.empID = empID;

09 }


11 {

12 return empID.ToString();

13 }

14 public int EmpID

15 {

16 get

17 {

18 return empID;

19 }

20 set

21 {

22 this.empID = value;

23 }

24 }


25 public int CompareTo(Object o)

26 {

27 Employee r = (Employee)o;

28 return this.empID.CompareTo(r.empID);

29 }

30 }


32 {


34 {

35 ArrayList empArray = new ArrayList();

36 Random r = new Random();

37 for (int i = 0; i < 5; i++)

38 {

39 empArray.Add(new Employee(r.Next(10) + 100));

40 }


41 // In tt c ni dung ca mng

42 for (int i = 0; i < empArray.Count; i++)

43 {

44 Console.Write("{0} ", empArray[i].ToString());

45 }

46 Console.WriteLine("\n");

47 // Sp xp li mng Employee da theo phng thc

CompareTo()

48 empArray.Sort();

49 // Hin th tt c ni dung ca mng Employee


51 {


53 }


55 }

56 }


Interface IComparer cung cp phng thc Compare(), so snh hai phn t trong mt tp hp c th t.

Phng thc Compare() thng c thc thi bng cch gi phng thc CompareTo() ca mt trong nhng i tng.

Nu chng ta mun to ra nhng lp c th c sp xp bn trong mt tp hp th chng ta cn thit phi thc thi IComparable.

Interface IComparer

001 using System;


003 public class Employee: IComparable

004 {


006 private int yearsOfSvc = 1;


008 {


010 }

011 public Employee(int empID, int yearsOfSvc)

012 {


014 this.yearsOfSvc = yearsOfSvc;

015 }


017 {

018 return "ID: " + empID.ToString() + ". Years of Svc: " +

yearsOfSvc.ToString();

019 }

020 // Phng thc tnh nhn i tng Comparer

021 public static EmployeeComparer GetComparer()

022 {

023 return new Employee.EmployeeComparer();

024 }

Interface IComparer

025 public int CompareTo(Object rhs)

026 {

027 Employee r = (Employee)rhs;

028 return this.empID.CompareTo(r.empID);

029 }

030 // Thc thi c bit c gi bi custom comparer

031 public int CompareTo(Employee rhs,

Employee.EmployeeComparer.ComparisionType which)

032 {

033 switch (which)

034 {

035 case Employee.EmployeeComparer.ComparisionType.EmpID:

036 return this.empID.CompareTo(rhs.empID);

037 case Employee.EmployeeComparer.ComparisionType.Yrs:

038 return this.yearsOfSvc.CompareTo(rhs.yearsOfSvc);

039 }

040 return 0;

041 }

042

043 // Lp bn trong thc thi IComparer

044 public class EmployeeComparer : IComparer

045 {

046 private Employee.EmployeeComparer.ComparisionType

whichComparision;

Interface IComparer

047 // nh ngha kiu lit k

048 public enum ComparisionType

049 {

050 EmpID, Yrs

051 };

052 // Yu cu nhng i tng Employee t so snh vi nhau

053 public int Compare(object lhs, object rhs)

054 {

055 Employee l = (Employee)lhs;

056 Employee r = (Employee)rhs;

057 return l.CompareTo(r, WhichComparision);

058 }

059 public Employee.EmployeeComparer.ComparisionType

WhichComparision

060 {

061 get

062 {

063 return whichComparision;

064 }

065 set

066 {

067 whichComparision = value;

068 }

069 }

070 }

071 }

072

Interface IComparer

073 public class Teser

074 {


076 {

077 ArrayList empArray = new ArrayList(); Random r = new

Random();

078 for (int i = 0; i < 5; i++)

079 {

080 empArray.Add(new Employee(r.Next(10) + 100,

r.Next(20)));

081 }

082 // Hin th tt c ni dung ca mng Employee


084 {

085 Console.Write("\n{0} ", empArray[i].ToString());

086 }


088 // Sp xp mng theo empID

089 Employee.EmployeeComparer c = Employee.GetComparer();

090 c.WhichComparision =

Employee.EmployeeComparer.ComparisionType.EmpID;

091 empArray.Sort(c);

Interface IComparer

092 // Hin th ni dung ca mng


094 {


096 }


098 // Sp xp mng theo yearsOfSvc

099 c.WhichComparision =

Employee.EmployeeComparer.ComparisionType.Yrs;

100 empArray.Sort(c);

101 // Hin th ni dung ca mng


103 {


105 }


107 }

108 }

Interface IComparer

Interface IComparer

Interface IDictionary l Interface i din chung cho

kiu tp hp dng cp key v value

IDictionary cung cp mt thuc tnh public l Item.

Thuc tnh Item cho php truy cp phn t trong tp

hp thng qua ton t ch mc ([]) ging nh truy cp

mng.

Interface IDictionary

Nhng i tng IDictionary cng h tr vng lp foreach bng vic thc thi phng thc GetEnumerator(), phng thc ny tr v mt IDictionaryEnumerator.

IDictionaryEnumerator

ArrayList

Lp ArrayList l mt kiu d liu ging nh kiumng nhng kch thc ca n c th c thayi ng theo yu cu.

Thuc tnh M t

Capacity Thuc tnh get hay set s thnh phn trong ArrayList.

Count Thuc tnh dng xc nh s phn t c trong ArrayList

IsFixedSize Thuc tnh kim tra xem kch thc ca ArrayList c c nh hay khng

IsReadOnly Thuc tnh kim tra xem ArrayList c thuc tnh ch c hay khng.

Phng thc M t

Add() Phng thc public thm mt i tng vo ArrayList

AddRange() Phng thc public thm nhiu thnh phn ca mt ICollection vo cui ca ArrayList

Clear() Xa tt c cc thnh phn t ArrayList

Clone() To mt bn copy

Contains() Kim tra mt thnh phn xem c cha trong mnghay khng

CopyTo() Phng thc public np chng sao chp mtArrayList n mt mng mt chiu.

GetEnumerator() Phng thc public np chng tr v mtenumerator dng lp qua mng

Item() Thit lp hay truy cp thnh phn trong mng ti v tr xc nh. y l b ch mc cho lp ArrayList.

ArrayList

ArrayList Phng thc M t

IndexOf() Phng thc public np chng tr v ch mc v tr u tinxut hin gi tr

Insert() Chn mt thnh phn vo trong ArrayList

InsertRange(0 Chn mt dy tp hp vo trong ArrayList

LastIndexOf() Phng thc public np chng tr v ch mc tr tr cuicng xut hin gi tr.

Remove() Xa s xut hin u tin ca mt i tng xc nh.

RemoveAt() Xa mt thnh phn v tr xc nh.

RemoveRange() Xa mt dy cc thnh phn.

Reverse() o th t cc thnh phn trong mng.

SetRange() Sao chp nhng thnh phn ca tp hp qua dynhng thnh phn trong ArrayList.

Sort() Sp xp ArrayList.

ToArray() Sao chp nhng thnh phn ca ArrayList n mt mngmi.

TrimToSize() Thit lp kch thc tht s cha cc thnh phn trongArrayList

01 using System;


03 public class Employee

04 {



07 {


09 }


11 {

12 return empID.ToString();

13 }

14 public int EmpID

15 {

16 get

17 {

18 return empID;

19 }

20 set

21 {

22 empID = value;

23 }

24 }

25 }

ArrayList

26 class Program

27 {


29 {

30 ArrayList empArray = new ArrayList();

31 ArrayList intArray = new ArrayList();

32 // a vo mng

33 for (int i = 0; i < 5; i++)

34 {

35 empArray.Add(new Employee(i + 100));

36 intArray.Add(i * 5);

37 }

38 // in tt c ni dung

39 for (int i = 0; i < intArray.Count; i++)

40 {

41 Console.Write("{0} ", intArray[i].ToString());

42 }


ArrayList

44 // in tt c ni dung ca mng


46 {


48 }


50 Console.WriteLine("empArray.Count: {0}", empArray.Count);

51 Console.WriteLine("empArray.Capacity: {0}",

empArray.Capacity);

52 }

53 }

ArrayList

Hng i l mt tp hp trong c th t votrc v ra trc (FIFO).

Queue (Hng i)

Thuc tnh M t

Count Thuc tnh tr v s thnh phn trong hng

i

IsReadOnly Thuc tnh xc nh hng i l ch c

IsSynchronized Thuc tnh xc nh hng i c ng b

SyncRoot Thuc tnh tr v i tng c th c s

dng

ng b truy cp Queue.

Phng thc M t

Clear() Xa tt c cc thnh phn trong hng i

Clone() To ra mt bn sao

Contains() Xc nh xem mt thnh phn c trong mng.

CopyTo() Sao chp nhng thnh phn ca hng i n

mng mt chiu tn ti

Dequeue() Xa v tr v thnh phn bt u ca hng i.

Enqueue() Thm mt thnh phn vo hng i.

GetEnumerator() Tr v mt enumerator cho hng i.

Peek() Tr v phn t u tin ca hng i v khng

xa n.

ToArray() Sao chp nhng thnh phn qua mt mng mi

Queue (Hng i)

01 using System;


03 class Program

04 {


06 {

07 Queue intQueue = new Queue();

08 // a vo trong mng

09 for(int i=0; i

25 // hin th hng i

26 Console.Write("intQueue values: "); PrintValues(intQueue);

27 }

28 public static void PrintValues(IEnumerable myCollection)

29 {

30 foreach (Object obj in myCollection)

31 Console.Write("{0} ", obj);

32 Console.WriteLine();

33 }

34 }

Queue (Hng i)

Ngn xp l mt tp hp m th t l vo trc ra sau hayvo sao ra trc (LIFO)

Hai phng thc chnh cho vic thm v xa t stack l Pushv Pop, ngoi ra ngn xp cng a ra phng thc Peektng t nh Peek trong hng i.

Stack (Ngn xp)

Thuc tnh M t

Count Thuc tnh tr v s thnh phn trong ngn xp

IsReadOnly Thuc tnh xc nh ngn xp l ch c

IsSynchronized Thuc tnh xc nh ngn xp c ng b

SyncRoot Thuc tnh tr v i tng c th c s dng

ng b truy cp Stack.

Stack (Ngn xp)

Phng thc M t

Clear() Xa tt c cc thnh phn trong ngn xp


Contains() Xc nh xem mt thnh phn c trong mng.

CopyTo() Sao chp nhng thnh phn ca ngn xp n

mng mt chiu tn ti

Pop() Xa v tr v phn t u Stack

Push() a mt i tng vo u ngn xp

Peek() Tr v phn t u tin ca ngn xp v khng

xa n.

ToArray() Sao chp nhng thnh phn qua mt mng mi

01 using System;


03 public class Program

04 {


06 {

07 Stack intStack = new Stack();

08 // a vo ngn xp

09 for (int i = 0; i < 8; i++)

10 {

11 intStack.Push(i * 5);

12 }

13 // hin th stack

14 Console.Write("intStack values: "); PrintValues( intStack

);

15 // xa phn t u tin

16 Console.WriteLine("\nPop: {0}", intStack.Pop());

17 // hin th stack


);

19 // xa tip phn t khc

20 Console.WriteLine("\nPop: {0}", intStack.Pop());

21 // hin th stack


);

Stack (Ngn xp)

23 // xem thnh phn u tin stack

24 Console.WriteLine("\nPeek: {0}", intStack.Peek());

25 // hin th stack

26 Console.Write("intStack values: "); PrintValues( intStack);

27 // khai bo mng vi 12 phn t

28 Array targetArray = Array.CreateInstance(typeof(int), 12);

29 for (int i = 0; i

44 public static void PrintValues(IEnumerable myCollection)

45 {

46 foreach (Object obj in myCollection)

47 Console.Write("{0} ", obj);

48 Console.WriteLine();

49 }

50 }

Stack (Ngn xp)

Hashtable l mt kiu t in trong c hai thnh phnchnh lin h vi nhau l key v value

Hashtable l kiu t in c ti u cho php vic truycp nhanh chng.

Hashtables

Thuc tnh M t

Count Thuc tnh tr v s thnh phn trong hashtable

IsReadOnly Thuc tnh xc nh hashtable l ch c

Keys Thuc tnh tr v mt ICollection cha nhngkha trong hashtable.

Values Thuc tnh tr v mt ICollection cha nhnggi

tr trong hashtable.

Phng thc M t

Add() Thm mt thnh phn mi vi kha v gi trxc

nh.Clear() Xa tt c i tng trong hashtable.

Item() Ch mc cho hastable


Contains() Xc nh xem mt thnh phn c tronghashtable.

ContainsKey() Xc nh xem hashtable c cha mt kha xc

nhCopyTo() Sao chp nhng thnh phn ca hashtable

n

mng mt chiu tn tiGetEnumerator() Tr v mt enumerator cho hashtable.

Remove() Xa mt thnh phn vi kha xc nh.

Hashtables

Hashtables

01 using System;



04 {


06 {

07 // to v khi to hashtable

08 Hashtable hashTable = new Hashtable();

09 hashTable.Add("00440123","Ngoc Thao");

10 hashTable.Add("00123001","My Tien");

11 hashTable.Add("00330124","Thanh Tung");

12 // truy cp qua thuc tnh Item

13 Console.WriteLine("myHashtable[\"00440123\"]: {0}",

hashTable["00440123"]);

14 }

15 }

16

Th vin System.IO cung cp nhiu lp dng cho vic c, ghifile cng nh vic thao tc vi file v th mc

Mt s lp chnh ca System.IO

System.IO

DriveInfo

Thuc tnh/ Phng thc c bn

M t

DriveFormat Tn ca file system, v d: NTFS/ FAT32

DriveType Cho bit lai a. Kiu d liu tr v l DriveType: CDRom, Fixed, Network, Ram,

Removable, Unknown

IsReady Cho bit a sn sng Read/Write.

Name Tn a

TotalFreeSpace Xem dung lng a trng

TotalSize Xem tng dung lng a

GetDrives() Ly danh sch a hin c

01 using System;

02 using System.IO;

03 class Test

04 {


06 {

07 DriveInfo[] allDrives = DriveInfo.GetDrives();

08 foreach (DriveInfo d in allDrives)

09 {

10 Console.WriteLine("Drive {0}", d.Name);

11 Console.WriteLine(" File type: {0}", d.DriveType);

12 if (d.IsReady == true)

13 {

14 Console.WriteLine(" Volume label: {0}",

d.VolumeLabel);

15 Console.WriteLine(" File system: {0}",

d.DriveFormat);

16 Console.WriteLine(

17 " Available space to current user:{0, 15}

bytes",

18 d.AvailableFreeSpace);

DriveInfo


20 " Total available space: {0, 15} bytes",

21 d.TotalFreeSpace);


23 " Total size of drive: {0, 15} bytes",

24 d.TotalSize);

25 }

26 }

27 }

28 }

DriveInfo

Thuc tnh/ phng thc c bn

M t

CreationTime Xem hoc thit lp thi gian to th mc

Exists Kim tra th mc tn ti trn a

FullName Ly ng dn ca ti th mc

LastAccessTime Cho bit thi gian cui cng th mc (file) c truy cp

Name Cho bit tn ca th mc

Parent Tr v th mc cha.

FileAttributes Attributes Cho bit thuc tnh ca th mc (file) FileAttributes l 1 enum gm cc gi tr nh: Directory, Readonly, Hidden,

Create() To th mc

Delete() Xa th mc

MoveTo() Di chuyn th mc

GetDirectories() Ly cc th mc con trong th mc

GetFiles Ly tt c cc tp tin trong th mc

DirectoryInfo

01 using System;

02 using System.IO;

03 class Test

04 {


06 {

07 // Specify the directories you want to manipulate.

08 DirectoryInfo di = new DirectoryInfo(@"c:\MyDir");

09 try

10 {

11 // Determine whether the directory exists.

12 if (di.Exists)

13 {

14 // Indicate that the directory already exists.

15 Console.WriteLine("That path exists already.");

16 return;

17 }

18 // Try to create the directory.

19 di.Create();

20 Console.WriteLine("The directory was created

successfully.");

DirectoryInfo

21 // Delete the directory.

22 di.Delete();

23 Console.WriteLine("The directory was deleted

successfully.");

24 }

25 catch (Exception e)

26 {

27 Console.WriteLine("The process failed: {0}",

e.ToString());

28 }

29 finally { }

30 }

31 }

DirectoryInfo

FileInfoThuc tnh/Phng thc c bn

M t

CreationTime Xem hoc thit lp thi gian to th mc

Exists Kim tra th mc tn ti trn a

Directory Tr v i tng th mc cha

DirectoryName Tr v chui ng dn (full path) ca th mc cha

Extension Tr v tn ui file (txt,bat,exe,)

Name Cho bit tn ca file

Attributes Cho bit thuc tnh ca file

CopyTo() Copy file n 1 ni khc

Create() To file

Delete() Xa file

MoveTo() Di chuyn file hoc i tn file

CreateText To StreamWriter ghi file

OpenText To StreamReader c file

ReplaceFile Thay i ni dung file

01 using System;

02 using System.IO;

03 class Test

04 {


06 {

07 string path = Path.GetTempFileName();

08 FileInfo fi1 = new FileInfo(path);

09 //Create a file to write to.

10 using (StreamWriter sw = fi1.CreateText())

11 {

12 sw.WriteLine("Hello");

13 sw.WriteLine("And");

14 sw.WriteLine("Welcome");

15 }

16 //Open the file to read from.

17 using (StreamReader sr = fi1.OpenText())

18 {

19 string s = "";

20 while ((s = sr.ReadLine()) != null)

21 {

22 Console.WriteLine(s);

23 }

24 }

FileInfo

25 try

26 {

27 string path2 = Path.GetTempFileName();

28 FileInfo fi2 = new FileInfo(path2);

29 //Ensure that the target does not exist.

30 fi2.Delete();

31 //Copy the file.

32 fi1.CopyTo(path2);

33 Console.WriteLine("{0} was copied to {1}.", path,

path2);

34 //Delete the newly created file.

35 fi2.Delete();

36 Console.WriteLine("{0} was successfully deleted.",

path2);

37 }

38 catch (Exception e)

39 {

40 Console.WriteLine("The process failed: {0}",

e.ToString());

41 }

42 }

43 }

FileInfo

c v vit d liu s c thc hin thng qualp Stream.

Stream l 1 lung d liu, n a d liu tim bt u n im cui.

System.IO.Stream l mt lp abstract nhngha mt s thnh vin c kh nng h tr vicc/vit ng b (synchronus) hoc khng ngb (asynchronous) i vi khi tr tin

X l c/ghi file

Thuc tnh/Phng thc c bn

M t

CanRead Lung c h tr c

CanSeek Lun c h tr di chuyn con tr

CanTimeOut Xc nh xem lung c timeout hay khng

CanWrite Lung c h tr ghi

Length Chiu di (theo bytes) ca lung

ReadTimeout Thit lp timeout cho phng thc Read

WriteTimeout Thit lp timeout cho phng thc Write

Position Ly hoc xc lp v tr con tr trong lung

Close() ng lung v gii phng ti ngun

Flush() y ton b d liu buffer trong lung ln trn thit b

Read() Thc thi phng thc c mng byte trn lung.

Seek() Di chuyn v tr con tr c

Write() Ghi mng byte ln trn lung

Stream Class

FileStream Class

Lp FileStream l lp dn xut t lp Stream. FileStream c mt s phng thc v thuc tnh ring.

Thuc tnh/Phng thc c bn

M t

Name Ly tn ca file

Lock() Kha file, trnh truy xut ng thi ln File

Unlock M kha file, c th truy xutng thi ln file

StreamReader

Thuc Tnh M t

BaseStream Tr v lung c

CurrentEncoding Ly thng tin nh dng ca lung ang s dng

EndOfStream Xc nh con tr c n cui lung cha

Phng thc M t

Close ng lung v gii phng ti nguyn

Peek Tr v gi tr k t tip theo trong lung, khng di chuyn con tr c.

Read Thc thi phng thc c mng cc k t trn lung.

ReadBlock c khi k t tip theo trn lung.

ReadLine c nguyn dng trn lung

ReadToEnd c tt c cc k t ti cui lung

StreamReader c th dng c vn bn

01 using System;

02 using System.IO;

03 class Test

04 {


06 {

07 try

08 {

09 // To mt Strea

Documents

2 - Ngon ngu C#