> Hmmm...  Is it possible to make a function an operator?

In C++, yes.

 >  E.g. you could say
 > int answer = 35 my_plus_function 35;
 > and get answer to be 70...???

Hmm. C++ operators have to be standard operators (ie. you can't "make
up" your own, but have to chose from the inbuilt set). The normal
requirement is to do something like this:

    string s = "hello" + " " + "world";

which is quite possible in C++ of you define both a conversion operator for
'char*' to 'string' and a '+' operator for type string.

class string
{
    .
    .
    operator char const *();
    string operator+(string const &);
    .
    .
};

There have been some very clever classes built up to take advantage of
conversion operators like this; one that comes to mind is the public domain
"val" class, which is a class that represents a polymorphic type,
with conversion operators to and from any of the C "basic" types;
int, long, float, char * etc.

--- MaltEd/2 1.0.b6