Ruby - Functions 2020

In this article, we'll learn how to use functions:

#!/usr/bin/ruby
# f1.rb
# How to function

def addition(n1, n2)
   return n1.to_i + n2.to_i
end

puts addition(3,9)

Output:

$ ./f1.rb
12

Note that we cannot change global variable within a function:

#!/usr/bin/ruby
# f2.rb
# How to function

x = 10

def change(x)
   x=99
end

change(x)
puts "x = #{x}"

Output:

$ ./f2.rb
x = 10

As we can see from the output, the variable x retains its value after the function call.

As a practice, here is a code for binary search:

#!/usr/bin/ruby
# bin.rb

def bin(a,n)
   s = 0
   e = a.length - 1
   mid = (s + e)/2
   while ( mid >= s and mid <= e)
      if (n < a[mid])
         e = mid - 1
      elsif (n > a[mid])
         s = mid + 1
      else
         return true
      end
      mid = (s + e)/2
   end
   return false
end

# input
arr = [1,3,5,7,9,11,13,15,17,19]

# try
find = [1,9,17,0,21,8]

find.each do |item|
   puts bin(arr,item)
end

Output:

true
true
true
false
false
false