Replace string replacing on itself

thandel used Ask the Experts™
I have a text field on a form... if a user enters Poly or Polycarb anywhere in the field I would like to replace it with Polycarbonate.

If I use this code the repalce doesn't provide the correct results.

Me.RefracAdd = Replace(Me.RefracAdd, "polycarb", "Polycarbonate")
Me.RefracAdd = Replace(Me.RefracAdd, "poly", "Polycarbonate")

Is this possible?
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DatabaseMX (Joe Anderson - Microsoft Access MVP)Database Architect / Application Developer
Top Expert 2007


This should work - RefracAdd assumed to be your text box name.

Private Sub RefracAdd_AfterUpdate ()

Me.RefracAdd = Replace(Me.RefracAdd, "polycarb", "Polycarbonate")
Me.RefracAdd = Replace(Me.RefracAdd, "poly", "Polycarbonate")

End Sub

What results are you getting and/or where do you have the code?

Most Valuable Expert 2015
Distinguished Expert 2018

It should work if you use it in the AfterUpdate event.

Top Expert 2010

This is something where I'd be tempted to use Regular Expressions.

1) Add this code to a regular VBA module:

Function RegExpReplace(LookIn As String, PatternStr As String, Optional ReplaceWith As String = "", _
    Optional ReplaceAll As Boolean = True, Optional MatchCase As Boolean = True, _
    Optional MultiLine As Boolean = False)
    ' Function written by Patrick G. Matthews.  You may use and distribute this code freely,
    ' as long as you properly credit and attribute authorship and the URL of where you
    ' found the code
    ' For more info, please see:
    ' This function relies on the VBScript version of Regular Expressions, and thus some of
    ' the functionality available in Perl and/or .Net may not be available.  The full extent
    ' of what functionality will be available on any given computer is based on which version
    ' of the VBScript runtime is installed on that computer
    ' This function uses Regular Expressions to parse a string, and replace parts of the string
    ' matching the specified pattern with another string.  The optional argument ReplaceAll
    ' controls whether all instances of the matched string are replaced (True) or just the first
    ' instance (False)
    ' If you need to replace the Nth match, or a range of matches, then use RegExpReplaceRange
    ' instead
    ' By default, RegExp is case-sensitive in pattern-matching.  To keep this, omit MatchCase or
    ' set it to True
    ' If you use this function from Excel, you may substitute range references for all the arguments
    ' Normally as an object variable I would set the RegX variable to Nothing; however, in cases
    ' where a large number of calls to this function are made, making RegX a static variable that
    ' preserves its state in between calls significantly improves performance
    Static RegX As Object
    If RegX Is Nothing Then Set RegX = CreateObject("VBScript.RegExp")
    With RegX
        .Pattern = PatternStr
        .Global = ReplaceAll
        .IgnoreCase = Not MatchCase
        .MultiLine = MultiLine
    End With
    RegExpReplace = RegX.Replace(LookIn, ReplaceWith)
End Function

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2) In your form code, replace those two lines with:

Me.Refrac.Add = RegExpReplace(Nz(Me.RefracAdd, ""), "\bpoly(carb)?\b", "Polycarbonate", True, False)

For more about Regular Expressions, please see:
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Most Valuable Expert 2012
Top Expert 2013

I think you need a conditional statement so that the text comes out right:

If instr(1,me.refracadd, "polycarb") > 0 then
    Me.RefracAdd = Replace(Me.RefracAdd, "polycarb", "Polycarbonate")
    Me.RefracAdd = Replace(Me.RefracAdd, "poly", "Polycarbonate")
end if

Top Expert 2010

>>Me.RefracAdd = Replace(Me.RefracAdd, "polycarb", "Polycarbonate")
>>Me.RefracAdd = Replace(Me.RefracAdd, "poly", "Polycarbonate")

The problem with those lines, as I see it:

1) An original entry of "polycarb" becomes "Polycarbonatecarbonate"

2) An original entry of "Polycarbonate" becomes "Polycarbonatecarbonateonate"

I went with RegExp because it allows me to specify word boundaries, i.e., \b  :)
Top Expert 2010

Same thing happens if we do a test like:

>>If instr(1,me.refracadd, "polycarb") > 0 then

If the text already contains "Polycarbonate", we're going to get a bad replacement.

This might work:

If instr(1,me.refracadd, "polycarbonate") > 0 then
    ' do nothing!!!
elseIf instr(1,me.refracadd, "polycarb") > 0 then
    Me.RefracAdd = Replace(Me.RefracAdd, "polycarb", "Polycarbonate")
    Me.RefracAdd = Replace(Me.RefracAdd, "poly", "Polycarbonate")
end if

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Of course, that will do us no good if this control contains long text which might have a mixture of polycarbonate, polycarb, and/or poly in the same entry...
Private Sub AfterUpdate()
  Me!RefreactAdd = Switch(Me!RefractAdd="Poly","Polycarbonate",Me!RefractAdd="Polycarb","PolyCarbonate")
End Sub


Gary your above code works great.... As I did others forgot that the in string looks for any part so the others did not work.  The only issues with your solution is if the user enters polycabonatevthen it leaves the field empty.  So I added a check to see if polycarbnate was entered correctly initially.
Top Expert 2010


I am very, very confused.  You indicated in yur question:

>>if a user enters Poly or Polycarb anywhere in the field [emphasis added]

Ray's suggestion applied to the entire field, not anywhere in the field.

Did you even try my suggestion in http:#a36480952 ?


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