Could we have a find_prev() as well?

[rhalbersma]

Hi! Could we have a find_prev() to go along the find_next()? That would allow efficient reverse iteration over all 1-bits. The code should be pretty much the reverse of find_next(), and using countl_zero instead of countr_zero as the bit intrinsic function.

[gennaroprota]

Hi Rein! Thanks for the suggestion :-).

Apparently, some people are confused by the name of find_first_off() (they mix it up with find_first_of(), although the latter wouldn't make much sense for a bitset), so I'm thinking of the following renames:

• find_first() → find_first_one()
• find_first_off() → find_first_zero()
• find_next() → find_next_one()
• find_next_off() → find_next_zero()

Once I have decided on that, I'll implement the member you suggested. It will likely be named find_previous_one().

[gennaroprota]

@rhalbersma: I sketched an implementation in PR #103. It adds a find_last_one(), too, although that's logically unnecessary, because a b.find_previous_one( i ) with i >= b.size() (e.g. i == npos) would find the last 1 bit. Please let me know what you think.