Each of the standard categories includes a family of facets
. Some of these implement formatting or parsing of a datum,
for use by standard or users' iostream operators
<< and
>>,
as members
put() and
get(), respectively
. Each such member function takes an
ios_base& argument whose members
flags(),
precision(),
and
width(),
specify the format of the corresponding datum (
[ios.base])
. Those functions which need to use other facets call its member
getloc()
to retrieve the locale imbued there
. Formatting facets use the character argument
fill
to fill out the specified width where necessary
.