zsh-4.3.4% s="5.2.314"
zsh-4.3.4% a=(${(s:.:)s})
zsh-4.3.4% print $a[1]
5
zsh-4.3.4% print $a[3]
314

bash 3.2.25(1)$ s="5.2.314"
bash 3.2.25(1)$ set -- ${s//./ }
bash 3.2.25(1)$ echo $1
5
bash 3.2.25(1)$ echo $3
314