Enable/disable requiredfieldvalidator control of textbox depending on selection of item in radiobuttonlist control

Hi,

  I have a webform with a radiobuttonlist control.

1.The user has to select one option from the radiobuttonlist control.   ie.The values are  a ,b , c ,Other. So I have used a requiredfield validator control for the radiobuttonlist control.

2.But if the user selects the option " Other",then there is a textbox control next to it.The user has to enter some value in the textbox control.So I have a requiredfield  validator control for the textbox .

3.But how to enable the requiredfield control for the textbox only if the user selects the option " Other"  and  Otherwise,disable the requiredfiled control of the textbox.

I have a button at the bottom of the webform.So please guide me how to implement this  feature.

 

Thanks,

pcs
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