o main returns int not void
o use return 0 at end of main when needed
o use braces to avoid potentially ambiguous else
o don't default to type int
o #ifdef 0 -> #if 0
Reviewed by: obrien and chuckr
newline must be part of the pattern space i.e. `echo a|sed -e P' must print
a
a
and not
aa
This is consistent with gnu sed, SunOS, Ultrix (and probably others!)
