VBA - Find certain strings in a worksheet - string

Question

I want to create either a macro or a UDF that can find cells in an excel worksheet that contains the following:
POxxx
PO xxxxxxx
PO# xxxxx
PO#xxxx
(With x being numbers)
The string could be at the start or the middle of cells.
In addition, the function/macro should not find cells that contain entries like CORPORATE, where PO is part of a word.
All the cells that contains qualifying data, should be highlighted.

Answer 1

This small UDF will return 1 is the match is present, otherwise 0
Public Function IsItThere(r As Range) As Long
Dim st As String
st = "0,1,2,3,4,5,6,7,8,9"
ary = Split(st, ",")
st = r.Text
IsItThere = 1
For Each a In ary
If InStr(1, st, "PO" & a) > 1 Then Exit Function
If InStr(1, st, "PO " & a) > 1 Then Exit Function
If InStr(1, st, "PO#" & a) > 1 Then Exit Function
If InStr(1, st, "PO# " & a) > 1 Then Exit Function
Next a
IsItThere = 0
End Function
You could also use Regular Expressions to find the pattern.

Answer 2

Try this:
Sub Tester()
Dim c As Range
For Each c In Selection.Cells
c.Interior.Color = IIf(RegexpTest(c.Value), vbRed, vbGreen)
Next c
End Sub
Function RegexpTest(v As String)
Static re As Object 'note static: you must reset the VB environment
' (press the "stop" button) if you edit the
' Pattern below
If re Is Nothing Then
Set re = CreateObject("VBScript.RegExp")
'"PO" then optional #, optional space, then 2-5 digits
re.Pattern = "PO#?\s?\d{2,5}"
re.ignorecase = True
End If
RegexpTest = re.test(v)
End Function