Question

What is the purpose of the std::remquo function? What is an example of when you would use it instead of the regular std::remainder function?

Answer 1

remquo first appeared in C99 before being in C++ and here is what the C99 rationale says about it:

The remquo functions are intended for implementing argument reductions which can exploit a few low-order bits of the quotient. Note that x may be so large in magnitude relative to y that an exact representation of the quotient is not practical.