# [LON-CAPA-users] regular expression

**H. K. Ng
**
lon-capa-users@mail.lon-capa.org

*Tue, 16 Aug 2005 10:41:41 -0400*

At 10:21 AM 8/16/2005, you wrote:
>*Why not use formula response instead of string?
*
formula response accepts answer such as
2/(4*x) whereas it should be
1/(2*x)
i.e., any multiple works. The algebra solution requires the student to
reduce to the lowest denominator.
>*On Aug 16, 2005, at 8:48 AM, H. K. Ng wrote:
*>*
*>>*Hi,
*>>*
*>>*Is there a way to construct the following regular expression? I
*>>*want the students to enter number1/(number2 * x) where number1 and
*>>*number2 are known integers. However, number2 can be 1, so that
*>>*means they can enter as number1/x and also, number1/(x) or number1/
*>>*(1*x). Question: For the last 2 answers, what I like to check is,
*>>*if they type the left parenthesis '(' then they need to enter the
*>>*right parenthesis ')'. I look in the Mastering Regular Expressions
*>>*book but could not find any info on how to check for an character.
*>>*
*>>*Thanks,
*>>*-hk
*>>*
*>>*_______________________________________________
*>>*LON-CAPA-users mailing list
*>>*LON-CAPA-users@mail.lon-capa.org
*>>*http://mail.lon-capa.org/mailman/listinfo/lon-capa-users
*>*
*>*_______________________________________________
*>*LON-CAPA-users mailing list
*>*LON-CAPA-users@mail.lon-capa.org
*>*http://mail.lon-capa.org/mailman/listinfo/lon-capa-users
*