#!/bin/bash

#-------------------------------------------------------------------------------
# Example 3 for Bash Tips show 17: Using "substring expansion" to extract
# associative array elements
#-------------------------------------------------------------------------------

#
# Make two indexed arrays each containing 10 letters. Note: this is not the
# best way to do this!
#
declare -a a1=( $(echo {a..j}) )
declare -a a2=( $(echo {k..t}) )

#
# Build an associative array using one set of letters as subscripts and the
# other as the values
#
declare -A hash
for ((i=0; i<10; i++)); do
    hash[${a1[$i]}]="${a2[$i]}"
done

#
# Display the associative array contents
#
echo "Contents of associative array 'hash'"
for key in "${!hash[@]}"; do
    printf '%s=%s\n' "hash[$key]" "${hash[$key]}"
done
echo

#
# Walk the associative array printing pairs of values
#
echo "Pairs of values from array 'hash'"
for ((i=1; i<10; i+=2)); do
    printf '%d: %s\n' "$i" "${hash[*]:$i:2}"
done