how to get a value of a variable from a controller to different view?

Hi,
a small question.How to get a value of a variable from a controller to
different view?
here is my code.
controller:
class CalController < ApplicationController
  def add
    @b=params[:number1].to_f
     @c=params[:number2].to_f
    if (@b==0 || @c==0)
      render :action=>"add1"
    else

     if params[:exp]== '1'
      @a=@b+@c
    elsif params[:exp]== '2'
      @a=@b-@c
      elsif params[:exp]== '3'
      @a=@b*@c
      elsif params[:exp]== '4'
      @a=@b/@c
     else
       @s="please select a choice"
       redirect_to :controller=> "home",:action =>"index"
    end
    end
  end
  def add1

  end

end

different view:

<html>
<body>
<h1><center><font color="blue">CALCULATOR</font></center></h1>

<%= form_tag(:controller=>"cal",:action => "add") do %>
<%= label_tag(:q1, "Enter first number:") %>
<%= text_field_tag(:number1) %> <br><br>
<%= label_tag(:q2, "Enter second number:") %>
<%= text_field_tag(:number2) %>
<br></br>
<%= label_tag(:q3, "Calculations:") %><br></br>
<div id="radio_buttons">
<%= radio_button_tag 'exp', 1 %>Add<br></br>
<%= radio_button_tag 'exp', 2 %>Sub<br></br>
<%= radio_button_tag 'exp', 3 %>Mul<br></br>
<%= radio_button_tag 'exp', 4 %>div<br></br>
</div>

<%= submit_tag("Submit") %>
<%= params[:s] %>
<% end %>

</body>
</html>

please help me out with this.i have used params but it is not working.
Thankyou.

If you redirect your page then you can not get that variable value to
your view
Only on render you have that variable value
And you can not have value in params unless you pass it in the arguments
at the time of the redirection

- Chirag Shah

Chirag Shah wrote in post #1013322:

If you redirect your page then you can not get that variable value to
your view
Only on render you have that variable value
And you can not have value in params unless you pass it in the arguments
at the time of the redirection

- Chirag Shah

hi Chirag
then how i do that?

for this part:
       @s="please select a choice"
       redirect_to :controller=> "home",:action =>"index"

i think you suppose to use notice or flash
redirect_to :controller=> "home",:action =>"index", :notice=> 'please
select a choice'
or
flash[:s] = "please select a choice"
redirect_to :controller=> "home",:action =>"index"

Hi All,

Is there a setting somewhere that I can change that will prevent scaffold-generated migrations from defaulting to allowing NULL values for columns?

Thanks!

**Leigh