Strings in VB - Part I

Contributed by Andrew On 29th November, 2006

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 Go4Expert Member
1May2008,03:07	#2
	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