Bài giảng Lập trình C# 2010: Chương 6 - ĐH Đồng Nai Công nghệ Đồng Nai

Bài giảng Lập trình C# 2010: Chương 6 - String Class có nội dung trình bày về: Constructor, String Field, String Operators, String Methods, DEMO String & Dictionary.

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characters.

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Constructor

There are many overload Constructors I would like to tell you the Constructor below:

String Constructor ( Char [])    

an array of Unicode characters

(new char[]{'H ','U ','I'});

M essageBox.Show (strH U I);

String strH U I = new String

(new char[]{'H ','U ','I'});

M essageBox.Show (strH U I);

Use string or String?

Use string or String?

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String Properties

Chars Gets the character at a specified character

position in the current String object

Length Gets the number of characters in the

current String object

( string strA, string strB )Description

indicates their relative position in the sort order

-1 strA is less than strB

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string strA, string strB,

bool ignoreCase )

Description

case, and returns an integer that indicates their relative position in

the sort order

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String Methods

Example

(“A", “a”,true);nRet=0

(“a", “A”,false);nRet=-1

(“A", “a”,false);nRet=1

public int CompareTo( string strB )

Description

whether this instance precedes, follows, or appears in the same

position in the sort order as the specified String (0 ; 1 ; -1)

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String Methods

Name

public bool Contains( string value )

Description

occurs within this string

Return true or false

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Determines whether the end of this string instance matches the

specified string when compared using the specified comparison

option

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String Methods

Name

public static string Format

(string format, params Object[] args )

Description

Replaces the format item in a specified string with the string

representation of a corresponding object in a specified array

strFormat = string.Format("Tỉ giá {0:d} = {1:c}", DateTime.Today,

22.3);

MessageBox.Show(strFormat);

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Author: Duy Thanh Tran – Phone : 0987773061 - Email: thanhxeiko@gmail.com – Blog: http://thanhxeiko.wordpress.com

character in this string

or -1 if it is not

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String Methods

Example

string str = "N guyễễ n Thị Long Lanh Chòng Chành Ánh Tuyễế t" ;

int nRet= str.IndexO f( 'T' );

public int IndexOf( string value )

Description

this instance

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String Methods

Example

string str = "Học! Học Nữa ! Học Mãi" ;

int nRet = str.IndexOf( "Học" );

Description

Reports the index of the first occurrence of the specified string in

to use for the specified string

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String Methods

Example

string strHUI = "Welcome C# 2010" ;

int nRet = strHUI.IndexOf( "WELCOME" ,

public int IndexOfAny( char[] anyOf )

Description

Reports the index of the first occurrence in this instance of any

character in a specified array of Unicode characters

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String Methods

Example

string str = "Không! không; có? có?" ;

int nRet=str.IndexOfAny( new char [] { '>' , '?' , ';' });

 nRet=12

string value )Description

Inserts a specified instance of String at a specified index position

in this instance

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Reports the index position of the last occurrence of a specified

Unicode character within this instance

-1 if it is not

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public int LastIndexOf( string value)

Description

Reports the index position of the last occurrence of a specified

string within this instance

The zero-based index position of value if that string is found, or -1 if it is not

If value is String.Empty  , the return value is the last index position in this instance

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String Methods

Example

string str = "Học ! Học Nữa ! Học Mãi";

int nRet = str.LastIndexOf("Học");

nRet =16

nRet = str.LastIndexO f("H Ọ C");

nRet = -1

comparisonType )

Description

Reports the index of the last occurrence of a specified string within

to use for the specified string

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String Methods

Example

string str = "Học ! Học Nữa ! Học Mãi" ;

int nRet = str.LastIndexOf( "HỌC" ,

StringComparison OrdinalIgnoreCase);

 nRet =16

public string Remove( int startIndex )

Description

Deletes all the characters from this string beginning at a specified

position and continuing through the last position

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int count )Description

Deletes a specified number of characters from this instance

beginning at a specified position

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char newChar )

Description

Returns a new string in which all occurrences of a specified

Unicode character in this instance are replaced with another

specified Unicode character

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string newValue )

Description

Returns a new string in which all occurrences of a specified string

in the current instance are replaced with another specified string

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String Methods

Example

string str = "Phải xem tài liệu trước khi tới lớp, tài liệu này rất quan trọng!" ;

str = str.Replace( "tài liệu" , "document" );

str = "Phải xem document trước khi tới lớp, document này rất quan trọng!" ;

Returns a string array that contains the substrings in this instance

that are delimited by elements of a specified Unicode character

array

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String Methods

Example

string str = "Trần văn tèo;21 tuổi;Chưa vợ;Côn Đảo";

string []strArr=str.Split(new char[]{';'});

foreach (string s in strArr)

public string[] Split( string[] separator, StringSplitOptions options )

Description

Returns a string array that contains the substrings in this string

that are delimited by elements of a specified string array A

parameter specifies whether to return empty array elements

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String Methods

Example

string str = "Trần văn tèo;;21 tuổi;Chưa vợ;Côn Đảo" ;

string []strArr=str.Split( new string [] { ";" }, StringSplitOptions.None);

M essageBox Show (strArr.Length+ "" );// 5

foreach ( string s in strArr)

string []strArr=str.Split( new string [] { ";" }, StringSplitOptions.R em oveEm ptyEntries);

M essageBox Show (strArr.Length+ "" );// 4

foreach ( string s in strArr)

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String Methods

Name

public bool StartsWith( string value )

Description

Determines whether the beginning of this string instance matches

the specified string

bool bStart=str.StartsWith( "<head>" );

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Determines whether the beginning of this string instance matches

the specified string when compared using the specified

comparison option

bool bStart=str.StartsWith( "<HEAD>" ,

StringComparison Ordinal);

MessageBox Show(bStart.ToString());False

bool bStart=str.StartsWith( "<HEAD>" ,

StringComparison OrdinalIgnoreCase);

True

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String Methods

Name

public string Substring( int startIndex )

Description

Retrieves a substring from this instance The substring starts at a

specified character position

string strSub = str.Substring(5);

MessageBox Show(strSub);

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String Methods

Name

public string Substring( int startIndex, int length )

Description

Retrieves a substring from this instance The substring starts at a

specified character position and has a specified length

string strSub = str.Substring(10,13);

MessageBox Show(strSub);

strSub = str.Substring(0,9);

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MessageBox Show(str);

 microsoft visual studio 2010

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MessageBox Show(str);

M ICRO SO FT VISU AL STU D IO 2010

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String Methods

Name

public string Trim()

Description

Removes all leading and trailing white-space characters from the

current String object

MessageBox Show(str.Length+ "" ); //35

MessageBox Show(str);

 " Microsoft Visual Studio 2010 "

string str = " Microsoft Visual Studio 2010 " ;

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String Methods

Name

public string TrimEnd( params char[] trimChars )

Description

Removes all trailing occurrences of a set of characters specified in

str=str.TrimEnd(new char [] { ' ' , '?' , '!' , '#' });

MessageBox Show(str.Length+ "" );// 28

MessageBox Show(str);

 "Microsoft Visual Studio 2010"

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String Methods

Name

public string TrimStart( params char[] trimChars )

Description

Removes all leading occurrences of a set of characters specified in

str=str.TrimStart(new char [] { ' ' , '?' , '!' , '#' });

MessageBox Show(str.Length+ "" );// 28

MessageBox Show(str);

 "Microsoft Visual Studio 2010"

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DEMO String & Dictionary

DEMO String & Dictionary

END