Operator< and strict weak ordering

Question

How to define operator< on n-tuple (for example on 3-tuple) so that it satisfy strict weak ordering concept ? I know that boost library has

Answer 1

The basic flow should be along the lines of: if the Kth elements are different, return which is smaller else go to next element. The code following assumes you don't have a boost tuple otherwise you would use get(tuple) and not have the problem to begin with.

if (lhs.first != rhs.first)
    return lhs.first < rhs.first;                
if (lhs.second != rhs.second)
    return lhs.second< rhs.second;
return lhs.third < rhs.third;