Ignoring errors

Morning,

I'm trying to use this basic formula for a column:

=A2-C2

However, I now need it to ignore it when it comes up with an error or put zero. So two formulas if anyone can help please:

=A2-C2 (and either give the numerical result, or if it would be an error come up blank)
and
=A2-C2 (and either give the numerical result, or it would be an error put the value 0 in)

Many thaks for any help you can give.