On Sunday, 22 April 2012 at 02:29:45 UTC, Jonathan M Davis wrote:
Regardless of whether it's the Big(O) complexity or the
constant factor that's
the problem here, clearly there's enough additional overhead
that it's causing
problems for Jay's particular case. It's also the sort of thing
that can be
easy to miss and then end up wondering why your code is so slow
(if it
actually matters in your particular situation).
- Jonathan M Davis
I haven't looked at strncmpi code, but I suspect it is a lot more
efficient. For example, in comparing
AbbbCdddEfffXabcdEfgh
AbbbCdddEfffYabcdEfgh
it is not necessary to do case conversion on anything except X
and Y, and if isUpper(X)==isUpper(Y) then X and Y can be compared
without conversion, and since X and Y are not equal the remaining
characters don't have to be converted.
The comment below worries me a little bit about std.string.icmp.
What if they are two 1MB strings that differ in he first
character? Does it really convert both strings to lower case
before comparing the first character?
http://dlang.org/phobos/std_string.html#icmp
"Technically, icmp(r1, r2) is equivalent to
cmp!"std.uni.toLower(a) < std.uni.toLower(b)"(r1, r2). "
