# Using a Regular Expression Validator

Learn how to create a regular expression validator and specify notification types for validating cell values in Spread.NET.

## Content

You can create a regular expression validator that checks to see if a cell's value matches the specified regular expression.
A validation error occurs if the value is not valid. You can also create an action, such as adding a backcolor to the cell, that lets the user know the value is invalid.
Use the **RegularExpressionValidator** class to create the validator. Specify a notification type such as [CellStyleNotify](/spreadnet/api/latest/online-win/FarPoint.Win.Spread/FarPoint.Win.Spread.CellStyleNotify.html). Then use the [AddValidators](/spreadnet/api/latest/online-win/FarPoint.Win.Spread/FarPoint.Win.Spread.SheetView.AddValidators.html) method to add the validator to a cell range.
![Regular Expression Validator](https://cdn.mescius.io/document-site-files/images/2238e618-a1fb-45a6-9ce5-9a4157bd2931/images/regularvalid.png)

## Using Code

The following example displays the invalid color if the value does not match the expression.

```csharp
//The error backcolor is displayed if the value is invalid
FarPoint.Win.Spread.CellStyleNotify cnotify = new FarPoint.Win.Spread.CellStyleNotify();
cnotify.InvalidCellStyle.BackColor = Color.Lime;
FarPoint.Win.Spread.RegularExpressionValidator rvalidator = new FarPoint.Win.Spread.RegularExpressionValidator();
rvalidator.Expression = "AA";
rvalidator.RegexOptions = System.Text.RegularExpressions.RegexOptions.IgnoreCase;
rvalidator.NullIsValid = true;
rvalidator.Actions.Add(cnotify);
fpSpread1.Sheets[0].AddValidators(new FarPoint.Win.Spread.Model.CellRange(1, 1, 1, 1), rvalidator);
```

```vbnet
'The error backcolor is displayed if the value is invalid
Dim cnotify As New FarPoint.Win.Spread.CellStyleNotify()
cnotify.InvalidCellStyle.BackColor = Color.Lime
Dim rvalidator As New FarPoint.Win.Spread.RegularExpressionValidator()
rvalidator.Expression = "AA"
rvalidator.RegexOptions = System.Text.RegularExpressions.RegexOptions.IgnoreCase
rvalidator.NullIsValid = True
rvalidator.Actions.Add(cnotify)
fpSpread1.Sheets(0).AddValidators(New FarPoint.Win.Spread.Model.CellRange(1, 1, 1, 1), rvalidator)
```

## See Also

[Using a Cell Comparison Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellcomparevalidator)
[Using a Character Format Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellcharformatv)
[Using a String Comparison Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellcomparestring)
[Using a Value Comparison Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellcomparevalue)
[Using an Encoding Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellencodingvalid)
[Using the Exclude List Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellexcludevalidator)
[Using the Include List Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellincludevalidate)
[Using a Pair Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellpairvalidate)
[Using the Range Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellrangevalidator)
[Using a Required Field Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellrequiredvalid)
[Using a Required Type Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellrequiretypev)
[Using a Surrogate Character Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-cellsurrogate)
[Using a Text Length Validator](/spreadnet/docs/latest/online-win/overview/spwin-devguide/spwin-interactcell/spwin-cellvalid/spwin-cellvalidation/spwin-celltextlvalid)