Printing array in bash script - bash

Question

I'm trying to write a script that takes integers as command line arguments, squares them and then shows the squares and the sum of the squares. Here's what I have:
#!/bin/bash
if [ $# = 0 ]
then
echo "Enter some numbers"
exit 1
fi
sumsq=0 #sum of squares
int=0 #Running sum initialized to 0
count=0 #Running count of numbers passed as arguments
while (( $# != 0 )); do
numbers[$int]=$1 #Assigns arguments to integers array
square=$(($1*$1)) #Operation to square argument first arg by itself
squares[$int]=$square #Square of each argument
sumsq=$((sumsq + square)) #Add square to total
count=$((count+1)) #Increment count
shift #Remove the used argument
done
echo "The squares are ${squares[#]}"
echo "The sum of the squares is $sumsq"
exit 0
I have it all working as it should except for the end where I need to display the squares. It is only printing the last square for some reason. I've tried changing e${squares[#]}" to ${squares[*]}", as well as double-quoting it, but it still only prints the last square. At some point, it printed the first square (which is expected) but I must have made a change somewhere and now it only seems to print the last one.
Any advice would be appreciated. Thanks!

Answer 1

The easy thing to do is simply delete the int variable altogether and replace it with count which you already increment within your loop, e.g.
sumsq=0 #sum of squares
count=0 #Running count of numbers passed as arguments
while (( $# != 0 )); do
numbers[$count]=$1 #Assigns arguments to integers array
square=$(($1*$1)) #Operation to square argument first arg by itself
squares[$count]=$square #Square of each argument
sumsq=$((sumsq + square)) #Add square to total
count=$((count+1)) #Increment count
shift #Remove the used argument
done
Example Use/Output
Making the change above:
$ bash squares.sh 1 2 3 4
The squares are 1 4 9 16
The sum of the squares is 30
(no, you don't such at programming, that's one issue new script writers could stare at for hours and not see -- and why running with bash -x scriptname to debug is helpful)
Update Following Comment Re: Difficulty
Above I only posted the changes needed. If it is not working for you, then I suspect a typo somewhere. Here is the complete script you can simply save and run:
#!/bin/bash
if [ $# = 0 ]
then
echo "Enter some numbers"
exit 1
fi
sumsq=0 #sum of squares
count=0 #Running count of numbers passed as arguments
while (( $# != 0 )); do
numbers[$count]=$1 #Assigns arguments to integers array
square=$(($1*$1)) #Operation to square argument first arg by itself
squares[$count]=$square #Square of each argument
sumsq=$((sumsq + square)) #Add square to total
count=$((count+1)) #Increment count
shift #Remove the used argument
done
echo "The squares are ${squares[#]}"
echo "The sum of the squares is $sumsq"
exit 0
As per the example above, run the script as:
bash squares.sh 1 2 3 4
(replace squares.sh with whatever name you gave to the file) If you have any problems, let me know because this is working quite well here, e.g.
bash squares.sh 1 2 3 4 5 6 7 8 9
The squares are 1 4 9 16 25 36 49 64 81
The sum of the squares is 285

Answer 2

Try this.
#!/usr/bin/env bash
case $# in
0) printf 'give me something!' >&2; exit 1;; ##: If no argument given exit!
esac
sumsq=0 #sum of squares
int=0 #Running sum initialized to 0
count=0 #Running count of numbers passed as arguments
while (( $# )); do
case $1 in
*[!0-9]*) printf '%s is not an integer!' >&2 "$1" ##: If argument is not an int. exit!
exit 1;;
esac
numbers[$((int++))]=$1 #Assigns arguments to integers array increment int by one
square=$(($1*$1)) #Operation to square argument first arg by itself
squares[$((int++))]=$square #Square of each argument increment int by one
sumsq=$((sumsq + square)) #Add square to total
count=$((count++)) #Increment count
shift #Remove the used argument
done
echo "The squares are ${squares[#]}"
echo "The sum of the squares is $sumsq"

Answer 3

Just iterate over given arguments
#!/bin/bash
for N in "$#"; { # iterate over args
squares+=( $((N*N)) ) # will create and then apend array squares
}
sqstr="${squares[#]}" # create string from array
echo "The squares are $sqstr" # string of squares will be substituted
echo "The sum of the squares is $((${sqstr// /+}))" # string will be substituted,
# spaces will be changed to +
# and sum will be calculated
Usage
$ ./test 1 2 3 4 5
The squares are 1 4 9 16 25
The sum of the squares is 55
Updated version
#!/bin/bash
for N do squares+=($((N*N))); done # iterate over args, create and then apend array squares
sqstr="${squares[#]}" # create string from array
echo "The squares are $sqstr" # string of squares will be substituted
echo "The sum of the squares is $((${sqstr// /+}))" # string will be substituted,
# spaces will be changed to +
# and sum will be calculated