BASH associative array printing

printf "%s\n" "${!array[@]}"
a2
a1
f50
zz
b1

printf "%s\n" "${array[@]}"
2
1
abcd
Hello World
bbb

printf "%s\n" "${!array[@]}" "${array[@]}" | pr -2t
a2                              2
a1                              1
f50                             abcd
zz                              Hello World
b1                              bbb

from : https://unix.stackexchange.com/questions/366581/bash-associative-array-printing