Increment a number in a string and zero fill it - regex

Question

In VB.NET, I would like to increment a number in a string and have it zeroed filled.
Here is the sample string with the 5 digit number:
R00099
What I would like returned after incrementing it by one:
R00100

Answer 1

No need for PadLeft:
Dim result = String.Format("R{0:D5}", number)
The D5 part in the formatter will format the number as a decimal number, using a fixed number of five digits, and filling the redundant digits with zeros.
More information can be found on the MSDN article about the decimal format specifier.

Answer 2

If the strings have been validated and are in the form specified then this should work
Private Function add1ToStringNoChecking(theString As String) As String
'assumes many things about the input instring
Return String.Format("{0}{1:d5}", _
"R", _
CInt(theString.Substring(theString.Length - 5, 5)) + 1)
End Function
Private Sub Button1_Click(sender As System.Object, _
e As System.EventArgs) Handles Button1.Click
Dim testS As String = "R00009"
Debug.WriteLine(add1ToStringNoChecking(testS))
End Sub

Answer 3

Assuming (with the regex tag) that you want to strip the number out first, and the input will always be in the form of letters followed by numeric then:
Function Increment(ByVal prefixedNumber As String) As String
Dim result As String = String.Empty
Dim numericRegex As New Text.RegularExpressions.Regex("^(\D*)(\d*)")
Dim numericMatch As Text.RegularExpressions.Match = numericRegex.Match(prefixedNumber)
If numericMatch.Success Then
Dim number As Integer
If Integer.TryParse(numericMatch.Groups(2).Value, number) Then
result = String.Format("{0}{1:D5}", numericMatch.Groups(1).Value, number + 1)
Else
' throw a non parse exception.
End If
Else
' throw a non match exception.
End If
Return result
End Function
Have a look at the Regex and Integer.TryParse documentation

Answer 4

Here is a handy function to accomplish the OP requirement:
Public Function Counter(ByVal StartingNumber As Int32, ByVal IncrementValue As Int32, ByVal TotalNumberLength As Int32, ByVal Prefix As String) As String
Dim Temp As Int32 = StartingNumber + IncrementValue
Dim Temp2 As String = CStr(Temp)
Line50:
If Temp2.Length < TotalNumberLength Then
Temp2 = "0" & Temp2
GoTo Line50
ElseIf Temp2.Length = TotalNumberLength Then
'do nothing
Else
'means error
Throw New System.Exception()
End If
Return Prefix & Temp2
End Function
Example of using the function:
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
'now test the function
MessageBox.Show(Counter(99, 1, 5, "R"))
'it will show R00100
End Sub
NOTE: This solution has been tested OK with Visual Studio 2010.