Uploaded by Thembani Thembani

Unit 09 String Manipulation using VB.net

advertisement
Part 9 - String Manipulation in VB .Net
String Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Using the string.length property . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Removing Characters from a String . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using TrimStart(), TrimEnd(), Trim() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removing Characters from a String . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using Remove() . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
3
4
4
Evaluating Strings with StartsWith() and EndWith() . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
ToUpper() and ToLower() Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
SubString Manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Replace Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
The Mid() Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
PadLeft() and PadRight() Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Insert Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
IndexOf() Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Like Operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1
String Length
String Length (Using the string.length property)
! Example 1:
Dim strName As String
Dim numOfChar As Integer
strName = "Smith"
numOfChar = strName.Length
Console.WriteLine("Name: {0}, Length: {1}", strName, numOfChar)
! Example 2:
Dim SSN As String
SSN = InputBox("SSN: XXX-XX-XXXX", "SSN")
Do While SSN.Length <> 11
SSN = InputBox("SSN: XXX-XX-XXXX", "SSN")
Loop
2
Removing Characters from a String
! Using TrimStart(), TrimEnd(), Trim()
! Example:
Dim myString As String
myString = "
Hello
"
Console.WriteLine("Original String:{0}:", myString)
'Remove leading spaces
Console.WriteLine("TrimStart
:{0}:", myString.TrimStart())
'Remove trailing spaces
Console.WriteLine("TrimEnd
:{0}:", myString.TrimEnd())
'Remove all spaces
Console.WriteLine("Trim
:{0}:", myString.Trim())
Original String:
Hello
TrimStart
:Hello
TrimEnd
:
Trim
:Hello:
:
:
Hello:
Dim myString As String
myString = "10.25 % "
Console.WriteLine("Original String:{0}:", myString)
'Remove trailing % and spaces
Console.WriteLine("TrimEnd
:{0}:", myString.TrimEnd("%", " "))
Original String:10.25 % :
TrimEnd
:10.25:
3
4
Removing Characters from a String
! Using Remove()
! To remove character from anywhere within the string.
! Syntax:
String.Remove(StartIndex, Count)
! Example:
Dim StrName As String = "John Cober"
Dim FName, LName As String
Fname = StrName.Remove(4, 6)
Lname = StrName.Remove(0, 5)
Console.WriteLine("Original String: {0}", StrName)
Console.WriteLine("First Name: {0}", FName)
Console.WriteLine("Last Name : {0}", LName)
5
Evaluating Strings with StartsWith() and EndWith()
! To determine whether a specific sequence of characters
occurs at the beginning or end of a string.
! Syntax:
String.StartsWith(SubString)
String.EndsWith(SubString)
! Example: (StartsWith)
Dim strDownPayment As String = "$2000.00"
Console.WriteLine("Original String: {0}", strDownPayment)
If strDownPayment.StartsWith("$") Then
strDownPayment = strDownPayment.TrimStart("$"c)
End If
Console.WriteLine("Final String : {0}", strDownPayment)
! Example: (EndsWith)
Dim URL As String = "www.iusb.edu"
If URL.EndsWith(".edu") Then
Console.WriteLine("University Site : {0}", URL)
ElseIf URL.EndsWith(".com") Then
Console.WriteLine("Company Site : {0}", URL)
ElseIf URL.EndsWith(".gov") Then
Console.WriteLine("Government Site : {0}", URL)
End If
6
ToUpper() and ToLower() Methods
! To access one or more characters contained in a string.
! Syntax:
String.ToUpper(String)
String.ToLower(String)
! Example:
Dim StrName As String = "John Cober"
Console.WriteLine("Original String: {0}", StrName)
Console.WriteLine("ToLower: {0}", StrName.ToLower())
Console.WriteLine("ToUpper: {0}", StrName.ToUpper())
Output
Original String: John Cober
ToLower: john cober
ToUpper: JOHN COBER
7
SubString Manipulation
! To access one or more characters contained in a string.
! Syntax:
String.SubString(StartIndex[, Count])
! Example:
Dim StrName As String = "John Cober"
Dim FName, LName As String
FName = StrName.Substring(0, 4)
LName = StrName.Substring(5)
Console.WriteLine("Original String: {0}", StrName)
Console.WriteLine("First Name: {0}", FName)
Console.WriteLine("Last Name : {0}", LName)
Output
Original String: John Cober
First Name: John
Last Name : Cober
8
Replace Method
! To Replace all occurrences of a sequence of characters
in a string with another sequence of characters.
! Syntax:
String.Replace(OldValue, NewValue)
! Example:
Dim strPhone As String = "1-800-111-0000"
Dim strNewPhone As String
Console.WriteLine("Original String: {0}", strPhone)
strNewPhone = strPhone.Replace("800", "877")
Console.WriteLine("Change Area Code: {0}", strNewPhone)
strNewPhone = strPhone.Replace("-", "")
Console.WriteLine("Remove Dashes: {0}", strNewPhone)
strNewPhone = strPhone.Replace("1", "2")
Console.WriteLine("Change 1's to 2's: {0}", strNewPhone)
Output
Original String: 1-800-111-0000
Change Area Code: 1-877-111-0000
Remove Dashes: 18001110000
Change 1's to 2's: 2-800-222-0000
9
The Mid() Statement
! To Replace a specific number of characters in a string
with characters from another string.
! Syntax:
Mid(TargetString, Start [,count]) = ReplacementString
! Example:
Dim StrName As String = "John Cober"
Console.WriteLine("Original String:
{0}", StrName)
Mid(StrName, 7, 1) = "yoooooooooooooooo"
Console.WriteLine("Change 7th character to 'y': {0}", StrName)
Mid(StrName, 6) = "yoooooooooooooooo"
Console.WriteLine("Change last name to 'yoooo': {0}", StrName)
remaining o's get disregarded
Mid(StrName, 1, 4) = "Joshua"
2 character get disregarded
Console.WriteLine("Change first name to Josh
'the
'last
: {0}", StrName)
Output
Original String:
Change 7th character to 'y':
Change last name to 'yoooo':
Change first name to Josh :
John Cober
John Cyber
John yoooo
Josh yoooo
10
PadLeft() and PadRight() Methods
! Insert characters at the beginning or end of the string.
! Syntax:
String.PadLeft(length[,character])
String.PadRight(length[,character])
‘Begining
‘End
! Example 1:
Dim StrName As String = "Hossein"
Console.WriteLine("Original String:{0}", StrName)
Console.WriteLine("Padleft (within 20 spaces: {0}",
StrName.PadLeft(20))
Console.WriteLine("Padleft with dots (within 20 dots)
StrName.PadLeft(20, "."c))
: {0}",
Console.WriteLine("PadRight with dots (within 20 spaces) : {0}",
StrName.PadRight(20, "."c))
Output
Original String:Hossein
Padleft (within 20 spaces:
Hossein
Padleft with dots (within 20 dots)
: .............Hossein
PadRight with dots (within 20 spaces) : Hossein.............
11
!
Example 2:
Dim intNum As Integer = 42
Dim strNum As String
strNum = intNum.ToString("P")
'Percent
strNum = strNum.PadLeft(12, "*"c)
Console.WriteLine(strNum)
strNum = intNum.ToString("C")
'Currency
strNum = strNum.PadLeft(12, "*"c)
Console.WriteLine(strNum)
Output
**4,200.00 %
******$42.00
12
Insert Method
! Inserting characters within a string
! Syntax:
String.Insert(StartIndex, Value)
! Example:
Dim strName As String = "Bob Smith"
Dim StrNew As String
StrNew = strname.insert(4, "J. ")
Console.WriteLine(StrNew)
Output
Bob J. Smith
13
IndexOf() Method
! Used to search a string to determine whether it contains
a specific sequence of characters.
! Syntax:
string.IndexOf(Value [,startIndex])
! Example:
Dim strMessage As String = "Have a Nice Day"
Dim intIndex As Integer
intIndex = strMessage.IndexOf("Nice")
'return the location for
"Nice"
Console.WriteLine(intIndex)
intIndex = strMessage.IndexOf("Mice")
'return -1 if the text is
not found
Console.WriteLine(intIndex)
intIndex = strMessage.IndexOf("Nice", 8)
'returns -1 because it
doesn't find it after the
8th location
Console.WriteLine(intIndex)
Output
7
-1
-1
14
Like Operator
! Used for pattern matching characters to determine
whether one string is equal to another string.
! Syntax:
string Like pattern
Pattern Matching
Characters
Matches in String
?
Any single character
*
Zero or more characters
#
any single digit 0-9
[charlist]
any single character in the charlist.
[a-z] matches any char that is lower
case.
[!charlist]
any single character not in the charlist.
[!a-z] matches any char that is not
lower case.
! Example:
strName.ToUpper() Like "T[IO]M"
'Matches Tom or Tim
MyString Like "###*"
'Matches a string with 3 digits
followed by any number of
characters
15
Download
Random flashcards
State Flags

50 Cards Education

Countries of Europe

44 Cards Education

Art History

20 Cards StudyJedi

Sign language alphabet

26 Cards StudyJedi

Create flashcards