How can I write set of all positive rational numbers

Question

How to write the set of all rational numbers?? From Cantor's matrix we can get the positive ones. Should I add corresponding negative values and a 0?

Answer 1

Use the order 0,1,-1, 2, -2, 3, -3, ... for the numerator and then apply the Cantor matrix. The denominator can be called positive wlog.