It's historical: length() can be used with the "special" values -1 and -2 to obtain the length of prefix() and suffix(), that's deprecated, and I don't *think* it's documented anywhere anymore, but was retained for backwards compatibility.
I guess after all this time it could be changed now, but I don't see it's causing any great harm either,
Can we at least fix the documentation of position() that has the wrong signature? My issue was that position(0) was ambiguous so I tried position(0U) as I read in the doc it was an unsigned int but this worked only on win32, not in linux x86_64! Then I discovered it was a size_type in the code. I know I could use the default value (0) instead so that it would not be ambiguous with char but it looks strange to me to call position() with no number. Frédéric