it is search string,it is used to identify the properties of
the objects that are changing in run time

it is search string,it is used to identify the properties of
the objects that are changing in run time

suppose if u want to check date field.  Date field like as 
mm/dd/yy. here we can use regular expression.

      ex:-mm/dd/yy
           here month cann't exceed 12
                Date cann't exceed 31 days
                yy cann't exceed present year
   
          for this we can regular expression
                [0-1][0-9]/[0-3][0-9]/07

      ex:- Window is there, name of the window is window1 
at first time.  but at the time of testing its variate like 
as window2, window3,...... at this time we can use regular 
expressions.
             
           regular expression for the above ex. is 

           !window*

      
     we can give regular expression in CONSTANT VALUE 
OPTIONS DIALOUGE BOX. u must enable the regular expression 
option. like this way we can give regular expression.

Regular expression is checking the pattern rather than constant value.

when you are doing web testing the browser name is keep changing, so by using .* we can handle that.