CODEWITHSUNDEEP
ruby-on-railsruby
Sachin R
Sachin R

Reputation: 11876

How to convert a string into integer without using ruby 'to_i' method

I want to convert given string into integer without using ruby to_i method.

Basically, I want to know how to_i was implemented or what is the best way to do that. Eg : 

a = '1234'

result 
a = 1234

Thanks in advance

Upvotes: 0

Views: 1216

Answers (3)

limekin
limekin

Reputation: 1944

Used to do it using this method in C, it might help you get an idea :

def too_i(number)
  return 0 if (lead = number[/^\d+/]).nil?
  lead.bytes.reduce(0) do |acc, chaar|
    # 48 is the byte code for character '0'.
    acc*10 + chaar - 48 
  end
end
too_i '123'
# => 123
too_i '123lol123'
# => 123
too_i 'abc123'
# => 0
too_i 'abcd'
# => 0

Upvotes: 1

mohamed-ibrahim
mohamed-ibrahim

Reputation: 11137

To be aware what is the main difference is Integer will throw an Exception if its not a valid integer, but to_i will try to convert as much as it can and you can rescue from Integer in case its not a valid integer as following

str = "123"
num = Integer(str) rescue 0   # will give you 123
num = str.to_i                # will give you 123

str = "123a"
num = Integer(str) rescue 0   # will give you 0 - will throw ArgumentError in case no rescue
num = str.to_i                # will give you 123

Upvotes: 0

Vrushali Pawar
Vrushali Pawar

Reputation: 3803

You can do this by following

2.1.0 :031 > str = "12345"
 => "12345" 
2.1.0 :032 > Integer(str) rescue 0
 => 12345

Upvotes: 4

Related Questions