Bash Script to Find Sum of Array Elements

Use a loop to add each element of the array to a sum variable like this: sum=0; for i in "${array[@]}"; do ((sum+=i)); done; echo $sum.

Examples

Inputarray=(1 2 3 4 5)

Output15

Inputarray=(10 20 30)

Output60

Inputarray=()

Output0

How to Think About It

To find the sum of array elements, start with a total of zero and add each number in the array one by one. This way, you accumulate the total sum by visiting each element exactly once.

Algorithm

1

Initialize a variable sum to 0

2

Loop through each element in the array

3

Add the current element's value to sum

4

After the loop ends, output the sum

Code

bash

array=(1 2 3 4 5)
sum=0
for i in "${array[@]}"; do
  ((sum+=i))
done
echo $sum

Output

15

Dry Run

Let's trace the array (1 2 3 4 5) through the code

1

Initialize sum

sum=0

2

Add first element

sum=0+1=1

3

Add second element

sum=1+2=3

4

Add third element

sum=3+3=6

5

Add fourth element

sum=6+4=10

6

Add fifth element

sum=10+5=15

Iteration	Current Element	Sum After Addition
1	1	1
2	2	3
3	3	6
4	4	10
5	5	15

Why This Works

Step 1: Initialize sum

We start with sum=0 because we want to add numbers starting from zero.

Step 2: Loop through array

The for loop goes through each element in the array one by one.

Step 3: Add elements

Inside the loop, ((sum+=i)) adds the current element to the total sum.

Step 4: Output result

After the loop finishes, echo $sum prints the total sum.

Alternative Approaches

Using while loop with index

bash

array=(1 2 3 4 5)
sum=0
index=0
while [ $index -lt ${#array[@]} ]; do
  ((sum+=array[index]))
  ((index++))
done
echo $sum

This uses a while loop and index to access elements, which is more manual but useful if you need index control.

Using printf and awk

bash

array=(1 2 3 4 5)
printf "%s\n" "${array[@]}" | awk '{sum+=$1} END {print sum}'

This pipes array elements to awk for summing, which is concise but depends on external tools.

Complexity: O(n) time, O(1) space

Time Complexity

The script loops once through all n elements, so time grows linearly with array size.

Space Complexity

Only a few variables are used regardless of array size, so space is constant.

Which Approach is Fastest?

The simple for-loop with arithmetic is fastest and uses no external commands, unlike the awk method.

Approach	Time	Space	Best For
For-loop with arithmetic	O(n)	O(1)	Simple, fast, pure Bash
While loop with index	O(n)	O(1)	When index control is needed
Printf with awk	O(n)	O(1)	Concise but uses external tool