RegExp for excluding special characters in a string.

I have tried with your expression:--

But some time it shows invalid msg for special characters .

Not all time you give .

You can try with following code:--

<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"

xmlns:s="library://ns.adobe.com/flex/spark"

xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600"

xmlns:local="*">

<fx:Script>

<![CDATA[

private var exp106:String = "^[a-zA-Z0-9 \-_]*$"

private function button1_clickHandler(event:MouseEvent):void{

regValidator.validate();

}

]]>

</fx:Script>

<fx:Declarations>

<!-- Place non-visual elements (e.g., services, value objects) here -->

<mx:RegExpValidator id="regValidator" expression=""

noMatchError="Not valid" source=""

flags="g" property="text" required="true" requiredFieldError="Please enter

string" />

</fx:Declarations>

<mx:VBox>

<s:TextInput id="textBox" />

<s:Button label="validate" click="button1_clickHandler(event)" />

</mx:VBox>

</s:Application