Bash: Convert String to Array

This is how you can convert a string into an array:

s="124890"
for i in $(seq 0 $((${#s}-1)))
do
     arr[$i]=${s:$i:1}
done

${#s} refers to the length of the string s, which in this case is 6.
${s:$i:1} returns a substring of s, starting from $i, of length 1.

The seq command is a new one for me. Unfortunately, it doesn't seem to be available on Solaris, only Linux. From the man pages:

NAME
       seq - print a sequence of numbers

SYNOPSIS
       seq [OPTION]... LAST
       seq [OPTION]... FIRST LAST
       seq [OPTION]... FIRST INCREMENT LAST

To see how you can convert a string of digits to an array in other languages, read this stackoverflow question.