Use @
to make the strings no longer use the escape character \
:
string regexPattern1 = @"^(\d{3}\.){2}\d{4}$";
string regexPattern2 = @"^((\(\d{3}\) ?)|(\d{3}-))?\d{3}-\d{4}$";
As a side note, I think you want the two if
s at the end to be a single if
with an or (||
) between the two conditions.