Multiplication in a Ruby array

Multiplication in an array (standard input)

Three integers are given separated by spaces. Output the value obtained by multiplying three integers.

For example

4 10 5

In this case 4 x 10 x 5


Please output.

How to do. 1


numbers = gets.split(' ').map(&:to_i)
a = 1
numbers.each do |number|
    a = a * number
puts a


numbers = gets.split(' ').map(&:to_i)

・ Call the input element with the get method -Split the character string separated by commas with the split method ・ Extract elements one by one with the map method and convert them to integers with to_i

a = 1
numbers.each do |number|
    a = a * number

・ Substitute 1 for a at ʻa = 1` (initial value) ・ Substitute the elements of numbers into the number variable and repeat the process below.

How to do. 2

How to inject method

numbers = gets.split(' ').map(&:to_i).inject(:*)

puts numbers

inject method (method to calculate the sum of arrays)

inject is a method that iterates like each and map.

The feature is that iterative calculations are performed using blocks.

Array object.inject {|initial value,element|Block processing}

It is described as.

The elements of the block are added by the array in the order of repetition, and the calculation is performed by processing the block.

Specify an operator using a symbol for inject

You can write the inject more stylishly by passing the operator as a symbol to the inject.

For example

It can be used in various situations such as *.

array = 1..6
p array.inject(:+) #Add all the elements of the array
p array.inject(3,:+) #Add all the elements of the array to the initial value of 3
p array.inject(:*) #Multiply all the elements of the array
p array.inject(3,:*) #Multiply all the elements of the array by the initial value of 3
p array.inject(100,:-) #Subtract the total value of array from 100

[Execution result]



The method using the inject method pointed out in the comment is smarter and easier to calculate! Thank you for your comment.

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