How to Find Sum of Array in Ruby: Simple Guide

In Ruby, you can find the sum of an array using the sum method directly on the array, like array.sum. This method adds all the numbers in the array and returns the total as a single number.

Syntax

The basic syntax to find the sum of an array in Ruby is:

• array.sum: Calls the sum method on the array to add all its elements.

This method works on arrays containing numbers and returns their total sum.

ruby

array = [1, 2, 3, 4, 5]
total = array.sum

Example

This example shows how to create an array of numbers and find their sum using the sum method.

ruby

numbers = [10, 20, 30, 40]
result = numbers.sum
puts result

Output

100

Common Pitfalls

Some common mistakes when summing arrays in Ruby include:

• Trying to sum arrays with non-numeric elements without handling them first.
• Using older Ruby versions where sum might not be available (before Ruby 2.4).
• Confusing sum with inject or reduce methods, which are more flexible but require more code.

Here is a wrong and right way example:

ruby

# Wrong: summing array with strings causes error
# array = [1, 'two', 3]
# puts array.sum

# Right: filter numbers before summing
array = [1, 'two', 3]
numbers_only = array.select { |e| e.is_a?(Numeric) }
puts numbers_only.sum

Output

4

Quick Reference

Method	Description	Example
sum	Adds all elements in the array	[1, 2, 3].sum #=> 6
inject(:+)	Adds elements using a block or symbol	[1, 2, 3].inject(:+) #=> 6
reduce(:+)	Alias for inject, adds elements	[1, 2, 3].reduce(:+) #=> 6

Key Takeaways

Use array.sum to quickly find the total of numeric arrays in Ruby.

Ensure all elements are numbers to avoid errors when summing.

For Ruby versions before 2.4, use inject(:+) or reduce(:+) as alternatives.

Filtering non-numeric elements before summing prevents runtime errors.

The sum method is simple and readable for beginners.