#!/bin/bash
# array-function.sh: Passing an array to a function and ...
#                   "returning" an array from a function


Pass_Array ()
{
  local passed_array   # Local variable!
  passed_array=( `echo "$1"` )
  echo "${passed_array[@]}"
  #  List all the elements of the new array
  #+ declared and set within the function.
}


original_array=( element1 element2 element3 element4 element5 )

echo
echo "original_array = ${original_array[@]}"
#                      List all elements of original array.


# This is the trick that permits passing an array to a function.
# **********************************
argument=`echo ${original_array[@]}`
# **********************************
#  Pack a variable
#+ with all the space-separated elements of the original array.
#
# Attempting to just pass the array itself will not work.


# This is the trick that allows grabbing an array as a "return value".
# *****************************************
returned_array=( `Pass_Array "$argument"` )
# *****************************************
# Assign 'echoed' output of function to array variable.

echo "returned_array = ${returned_array[@]}"

echo "============================================================="

#  Now, try it again,
#+ attempting to access (list) the array from outside the function.
Pass_Array "$argument"

# The function itself lists the array, but ...
#+ accessing the array from outside the function is forbidden.
echo "Passed array (within function) = ${passed_array[@]}"
# NULL VALUE since the array is a variable local to the function.

echo

############################################

# And here is an even more explicit example:

ret_array ()
{
  for element in {11..20}
  do
    echo "$element "   #  Echo individual elements
  done                 #+ of what will be assembled into an array.
}

arr=( $(ret_array) )   #  Assemble into array.

echo "Capturing array \"arr\" from function ret_array () ..."
echo "Third element of array \"arr\" is ${arr[2]}."   # 13  (zero-indexed)
echo -n "Entire array is: "
echo ${arr[@]}                # 11 12 13 14 15 16 17 18 19 20

echo

exit 0

#  Nathan Coulter points out that passing arrays with elements containing
#+ whitespace breaks this example.