Arithmetic with array elements in bash

Question

I'm using bash and trying to add all elements of an array that was created from a file.

while read line; do
    array=($line);
    sum=0
    length=${#array[@]}
    for i in ${array[@]:0:$length}; do
       sum=$[$sum+${array[i]}]   #<--- this doesn't work?
    done
    echo $sum
done < $1

edit: I should have been clearer why i want to use array splitting in for loop

The input may be ------> david 34 28 9 12

And I want to print ---> david 83

So I would like to loop through all elements accept the first one. so i would use:

length=$[${#array[@]} - 1]
for i in${array[@]:1:$length}

because of this i can't use:

for i in "${array[@]}"

Answer 1

Try using expr to add two expression something like:

sum=$(expr "$sum" + "${arr[i]}")

Or

sum=$((sum + arr[i]))


echo "11 13" >test.txt 
echo "12" >>test.txt

while read -a line; do ##read it as array
    sum=0
    for ((i=1; i < ${#line}; i++)); do ##for every number in line
       sum=$(expr "$sum" + "${line[i]}") ## add it to sum
    done
    echo $line[0] $sum ##print sum
done < test.txt
Output
36

After OP's edit:

echo "ABC 11 13" >test.txt echo "DEF 12" >>test.txt

while read -a line; do ##read it as array
sum=0
for ((i=1; i < $((${#line[@]})); i++)); do ##for every number in line
   sum=$(expr "$sum" + "${line[i]}") ## add it to sum
   if [[ $i -eq $((${#line[@]}-1)) ]]
   then
       echo "${line[0]} $sum" ##print sum
       sum=0
   fi
done
done < test.txt
Output:
ABC 24
DEF 12