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