Strings in VB - Part I

Andrew's Avatar author of Strings in VB - Part I
This is an article on Strings in VB - Part I in Visual Basic [VB].

Substrings



Left, Right and Mid are three Visual Basic functions to locate sections of a string. All of the following examples use the string "strExample" with the following value.

strExample = "Please try to substring this"

The Left function returns the requested number of characters from the left side of the string.

Code: VB
Me.Print Left(strExample, 10)
Returns, "Please try"

The Right function returns the requested number of characters from the right side of the string.

Code: VB
Me.Print Right(strExample, 18)
Returns, "do what you can do"

The Mid function returns the middle of a string. It takes three parameters, the string, the starting position and the length of the string to be returned.

Code: VB
Me.Print Mid(strExample, 8, 6)
Returns, "try to"

The Len function is used to determine the length of a string. The next example uses the Len and the Mid function to print a string of text down the form.
Code: VB
Dim counter As Integer

Const strExample As String = "Please try to do what you can do"
 
For counter = 1 To Len(strExample)
    Me.Print Mid(strExample, counter, 1)
Next counter

String Concatenation



Strings are joined together using the & operator.
Code: VB
Dim strFirst As String, strSecond As String, strResult As String
strFirst = "Too "
strSecond = "bad!"
strResult = strFirst & strSecond
Me.Print strResult
The concatenation operator is useful for building up long strings a bit at a time.
Code: VB
Dim strSQL As String

strSQL = "SELECT Surname, TelNo " & _
"FROM Customer " & _
"ORDER BY Surname"

Searching a String



InStr and InStrRev are two Visual Basic functions to locate one string inside another. InStr locates the first occurrence of the string, and InStrRev locates the last occurrence.

Code: VB
Const strExample As String = "Please try to do what you can do"
Dim pos As Integer
pos = InStr(strExample, "do")
If pos > 0 Then
    Me.Print "Found first occurrence of string at position " & pos
Else
    Me.Print "String not found"
End If
Returns, "Found first occurrence of string at position 15"
Code: VB
Const strExample As String = "Please try to do what you can do"
Dim pos As Integer
pos = InStrRev(strExample, "do")
If pos > 0 Then
    Me.Print "Found last occurrence of string at position " & pos
Else
    Me.Print "String not found"
End If
Returns, "Found last occurrence of string at position 31"
Steel9561's Avatar, Join Date: Apr 2008
Go4Expert Member
I think that the Mid function is often used whenever you need to extract a certain string from a big string. I often do it in the programs I do. You extract only what you want and then you work with that string or display it to the user in a listbox, combo box, etc..

Luis Lazo

Last edited by shabbir; 1May2008 at 11:28.. Reason: Confine links to signature
articlechamp's Avatar, Join Date: Apr 2009
Newbie Member
thnks its wnderful