[CR integrated in VS 2005] - sum of string fields

Question

Hello,
i am discovering CR,
and i am trying to do the sum of a field (number) but declared as string. the declaration of the field cannot be changed (string in the database).
so i want to do the sum of this field.
i wonder if it is possible, and if yes, how.
maybe something like a formula.
I saw the functions: ToNumber () and Cdbl() for conversion, and Sum().
If someone has an idea, i will be very interested.
PS: sorry if my question is not understandable, i'm french. If you don't understand it, i would rewrite it.
thank you!

Answer 1

thank you.
I could convert, but the problem is to make the sum of the conversion.
i would like to do something like:
Sum(ToNumber ()) but CR does not accept it.
Maybe by using a variable in a formula (but i don't know where):
shared numbervar total;
total = total+ToNumber({MyField});
and when printing a formula field at the bottom of the report to show the total:
shared numbervar total;
ToText (total);