Iterate over an array using POSIX Shell

iterate_shell_array.sh

#!/bin/sh
# Iterate over an array using POSIX Shell

# Initial data
ARR="a:b:c:d"

# Iteration. Do whatever is needed instead of 'echo "$CAR"'.
CDR="${ARR}:"; while [ -n "$CDR" ]; do CAR=${CDR%%:*}; echo "$CAR"; CDR=${CDR#*:}; done; unset CAR CDR

# IMPORTANT!!! Add semicolon to the end of an array (IT="${ARR}:") to make stop condition working.
#              Otherwise you will get infinite loop.