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-   -   addition using array values into a variable not possible? (https://www.linuxquestions.org/questions/programming-9/addition-using-array-values-into-a-variable-not-possible-914726/)

olof_ 11-21-2011 11:19 AM
addition using array values into a variable not possible?
 
Hi there.

I am trying to add every value in an array together in a single variable. The script is working, but throws an error:

syntax error: operand expected (error token is "+")
Is it not possible to add values from an array into a non-array variable?

Code:
echo Input some numbers, separated by a space please:
read -a choice

amount=${#choice[@]}

for a in `seq 0 $amount`; do
sum=$(($sum+${choice[$a]}))
done

echo The result after adding all numbers is: $sum
Thanks in advance.

firstfire 11-21-2011 11:36 AM
Hi.
This should work:
Code:
echo Input some numbers, separated by a space please:
read -a choice

amount=${#choice[@]}

for a in `seq 0 $amount`; do
sum=$((sum + choice[$a]))
done

echo The result after adding all numbers is: $sum

grail 11-21-2011 11:52 AM
There is some more overhead that is not really required:
Code:
#!/bin/bash

echo Input some numbers, separated by a space please:
read -a choice

for a in ${!choice[*]}
do
    ((sum+=choice[a]))
done

echo The result after adding all numbers is: $sum

olof_ 11-21-2011 02:44 PM
Thank you very much!
Really impressively quick answers.

David the H. 11-21-2011 04:00 PM
Or how about this?

Code:
$ choice=( 1 2 3 4 5 )
$ IFS=+

$ echo $(( ${choice[*]} ))
15
It may not work correctly with negative numbers though.


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