Arithmetic with array elements in bash
Solution 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]} $sum" ##print sum
sum=0
fi
done
done < test.txt
Output:
ABC 24
DEF 12
Solution 2
If you want to sum the numbers in each lines of the file using a loop in bash you could do
#!/bin/bash
while read line; do
array=($line);
sum=0
length=${#array[@]}
for i in ${array[@]:0:$length}; do
sum=$[$sum+$i]
done
echo $sum
done < "$1"
The difference with your code is that i
is the element in the array, not the index.
However, possessing files in bash is rather slow. You would be probably better off to do the task in awk, like this for example:
awk '{s=0;for(i=1;i<=NF;i++) s+=$i;print s}' file
![Vaderico](https://i.stack.imgur.com/zHivq.jpg?s=256&g=1)
Vaderico
Updated on June 19, 2022Comments
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Vaderico about 2 years
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[@]}"
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Vaderico about 9 yearssum=$(expr "$sum" + "${arr[i]}") : gives me an error. sum=$((sum + arr[i])) : doesnt work :/ and gives no error
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SMA about 9 yearsIhave modified your script.
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Vaderico about 9 yearsI can't use that for loop, I explain why in the edited question.
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Vaderico about 9 yearsI can't use that for loop, I explain why in the edited question.
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SMA about 9 yearshow about
for i in "${!line[@]}"; do
orfor ((i=0; i < ${#line}; i++))
orfor ((i=0; i < ${length}; i++))
Also dont keep on editing the question with additional requirements. -
user000001 about 9 years@Vaderico Still
i
is the value, not the index. See edit. Also you have a typo in the question. It should belength=${#array[@]}
and notlength=${#arr[@]}
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Vaderico about 9 yearsIt isn't the loop that is the problem, I am successfully itereating from index 1 to array length. It's just the arithmetic that is the problem. It isn't accepting the addition of an integer and a array string number.
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Vaderico about 9 yearsokay that works aswell, thanks for the help! much appreciated