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DONG NAI UNIVERSITY OF TECHNOLOGY


DONG NAI UNIVERSITY OF TECHNOLOGY

String Class
Represents text as a series
of Unicode characters.


DONG NAI UNIVERSITY OF TECHNOLOGY

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

String Constructor ( Char [])
Initializes a new instance of the String
class to the value indicated by an array
of Unicode characters.


DONG NAI UNIVERSITY OF TECHNOLOGY

Constructor
string strHUI = new string
(new char[]{'H','U','I'});
MessageBox.Show(strHUI);
Use string or String?
String strHUI = new String
(new char[]{'H','U','I'});

MessageBox.Show(strHUI);


DONG NAI UNIVERSITY OF TECHNOLOGY

String Fields
Empty
Represents the empty string.
This field is read-only.
string strName = string.Empty;


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String Operators
Name
Equality(==)
“a”==“A”?false
“a”==“a”?true

Description
Determines whether
two specified strings
have the same value.

Inequality(!=)
“a”!=“A”?true
“a”!=“a”?false

Determines whether

two specified strings
have different values.


DONG NAI UNIVERSITY OF TECHNOLOGY

String Properties
Name
Chars

Description
Gets the character at a
specified character position
in the current String object.

char ch = strHUI[0];
Length Gets the number of
characters in the
current String object.
int nSize = strHUI.Length;


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Name
public static int Compare
( string strA, string strB )
Description

Compares two specified String objects
and returns an integer that indicates
their relative position in the sort order
0 strA equals strB
1 strA is greater than strB
-1 strA is less than strB


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Example
int nRet = string.Compare(“A", “a");
nRet=1
int nRet = string.Compare(“a", “A");
nRet=-1
int nRet = string.Compare(“a", “a");
nRet=0


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Name
public static int Compare(
string strA, string strB,
bool ignoreCase )
Description

Compares two specified String objects
,ignoring or honoring their case, and
returns an integer that indicates their
relative position in the sort order


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods
Example
int nRet = string.Compare
(“A", “a”,true);nRet=0
int nRet = string.Compare
(“a", “A”,false);nRet=-1
int nRet = string.Compare
(“A", “a”,false);nRet=1


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Name
public int CompareTo( string strB )
Description
Compares this instance with a
specified String object and indicates
whether this instance precedes,
follows, or appears in the same
position in the sort order as the

specified String. (0 ; 1 ; -1)


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Example
string strA = “A”;
string strB = “B”;
int nRet = strA.CompareTo(strB);
nRet=-1
string strA = “A”;
string strB = null;
int nRet = strA.CompareTo(strB);
nRet=1


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Name
public static string Copy(string str)
Description
Creates a new instance of String with
the same value as a specified String.
string str = string.Copy("Teo");
string str1 = "Ti";
string str2 =string.Copy(str1);

DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Name
public bool Contains( string value )
Description
Returns a value indicating whether the
specified String object occurs within
this string
Return true or false


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Example
string strA = "Trần Văn Tèo";
string strB = "Văn";
bool bRet = strA.Contains(strB);
if (!bRet)
MessageBox.Show("Không có
["+strB+"] trong ["+strA+"]");
else
MessageBox.Show("Có [" + strB + "]
trong [" + strA + "]");

DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Name
public bool EndsWith( string value )
Description
Determines whether the end of this
string instance matches the specified
string
Return true or false


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Example
string strA = "<div>Tèo </div>";
string strB = "</div>";
bool bRet = strA.EndsWith(strB);
if (bRet)
MessageBox.Show("có [" +
strB+"] ở cuối chuỗi");
else
MessageBox.Show("Ko có [" +
strB + "] ở cuối chuỗi");

DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Name
public bool EndsWith( string value,
StringComparison comparType )
Description
Determines whether the end of this
string instance matches the specified
string when compared using the
specified comparison option


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods
Example

string strA = "<div><div>Tèo</div></div>";
string strB = "</DiV>";
bool bRet = strA.EndsWith(strB,
StringComparison.OrdinalIgnoreCase);
if (bRet)
MessageBox.Show("có [" + strB+"] ở
cuối chuỗi");
else
MessageBox.Show("Ko có [" + strB +
"] ở cuối chuỗi");

DONG NAI UNIVERSITY OF TECHNOLOGY

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


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Example
string strFormat;
strFormat = string.Format("Tỉ giá {0:d}
= {1:c}", DateTime.Today, 22.3);
MessageBox.Show(strFormat);


HO CHI MINH UNIVERSITY OF INDUSTRY

Author: Duy Thanh Tran – Phone : 0987773061- Email: – Blog:

DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods

Name
public int IndexOf( char value )
Description
Reports the index of the first
occurrence of the specified Unicode
character in this string.
The zero-based index position
of value if that character is found, or -1
if it is not


DONG NAI UNIVERSITY OF TECHNOLOGY

String Methods
Example

string str = "Nguyễn Thị Long Lanh Chòng
Chành Ánh Tuyết";
int nRet=str.IndexOf('T');
nRet=7
int nRet=str.IndexOf(‘t');
nRet=41
int nRet=str.IndexOf(‘Ă');
nRet=-1