Conditional Reg Ex Help

See more:

C#

regular-expression

Hello all,
i am trying to write a regular expression for a html like parser. I want help at a point in parsing the tags, such that it looks for the matching end tag if and only if there is a starting tag written before.

So for example, if in the middle of a string a user can type <a href=""> </a>, and it should check for </a> only if <a> is there, not otherwise. How to match it conditionally ?

Thanks.