These functions are the same as @code{printf}, @code{fprintf}, and
@code{sprintf}, respectively, except that they are called with a
@code{va_list} instead of a variable number of arguments. Note that
they do not call @code{va_end}; this is the application's
responsibility. In @libib{} they are implemented in terms of the
nonstandard but common function @code{_doprnt}.