man 3p printf
man 3 printf
The above two man page gives different info of printf.
What's different for man 3 and man 3p?
$ man -k printf | grep '^printf'
printf (1) - format and print data
printf (1posix) - write formatted output
printf (3) - formatted output conversion
printf (3posix) - print formatted output
You have probably installed the manpages-posix and manpages-posix-dev packages on your system, as I have. This also gives you the POSIX-prepared manpages, which is an excellent way to determine if you're relying on behavior specific to your system or standardized behavior.