Use 'Formulas' and 'Validation' on my Forms?

A 'formula' allows you to calculate a number. For example, you would use a 'formula' to calculate the total on an order form. In essence, the output of a 'formula' is a number.

A 'validation' allows you to verify that the data on a form is valid. For example, if you have a form where the user is supposed to choose and check 3 checkboxes out of 5, a 'validation' could ensure that they checked exactly three. In essence, the output of a 'validation' is an error message--or no error message, if all is well.

You build formulae and validations in much the same way. You use the same arithmetic operations for both:

+	Addition
-	Subtraction
*	Multiplication
/	Division
%	Modular arithmetic
( )	Parentheses (for grouping)
==	Is equal?
!=	Is not equal?
>	Is greater than?
<	Is less than?
>=	Is greater than or equal?
<=	Is less than or equal?

You build formulae and validations using Numbers and Checkboxes from your form. (For checkboxes, SET = 1 and UNSET = 0.)

Example 1: A Simple Formula

Suppose your form looks like this:

Check the options that you want: Option 1 ($25):  Option 2 ($30): 

If your User Datums for the checkboxes are {Option1} and {Option2}, the formula for the total would be:

{Option1}*25 + {Option2}*30

Suppose they check {Option1} but not {Option2}. Then {Option1} evaluates to '1' and {Option2} evaluates to 0:

(1)*25 + (0)*30
= 25 + 0
= 25

Example 2: A Simple Validation

Using the same form above (Example 1), if you'd like to verity that they checked at least one checkbox, the validation could be:

{Option1} + {Option2} > 0

Suppose they check {Option1} but not {Option2}. Then {Option1} evaluates to '1' and {Option2} evaluates to 0:

(1) + (0) > 0
1 > 0

which is TRUE, meaning that the form data is valid.

Suppose they don't check either checkbox. Then both {Option1} and {Option2} evaluate to 0:

(0) + (0) > 0
0 > 0

which is FALSE, meaning that the form data is NOT valid, and ProPageManager™ will display your error message.