CODEWITHSUNDEEP
ruby
Ryan Haining
Ryan Haining

Reputation: 36802

Convert string to Float or Fixnum

Given a string from user input, I want to convert it to a Fixnum or Integer if the string is a valid int. I do not want to convert to an int if the string is a float. If that fails, I then want to try to convert the string to a Float. If the string is not either of these I intend to just raise an exception.

It seems that String#to_i just truncates any Float value rather than providing any sort of error. I know I could do some regexing to determine whether a String is a valid int, but it seems like there should be some built-in conversion that fails if a String has anything other than digits. Am I missing something?

For example. I want something like this that fails instead of returning 1

irb(main):092:0> "1.4".to_i
=> 1
irb(main):093:0> "1.4e5".to_i
=> 1

Upvotes: 0

Views: 3186

Answers (4)

D.Shmelev
D.Shmelev

Reputation: 41

My solution

def typing(value)
  if value.to_i.to_s == value
    value.to_i
  elsif value.to_f.to_s == value
    value.to_f
  else
    value
  end
end

Upvotes: 2

Billy Chan
Billy Chan

Reputation: 24815

I don't like rescue so this is my version :)

def to_fi(str)
  if str.to_i == str.to_f
    str.to_i
  else
    str.to_f
  end
end

a = "1"
to_fi a
#=> 1

a = "1.0"
to_fi a
#=> 1

a = "1.2"
to_fi a
#=> 1.2

Upvotes: 0

rderoldan1
rderoldan1

Reputation: 4088

.to_f or .to_f by definition never raise error and if they can't convert the string return 0. You can use the clases Integer and Float.

this method return the error raised or float number if first can convert to integer

def validate_number(string)
   begin
    Integer(string)
    Float(string)
   rescue => e
    e
   end
end

Upvotes: -1

sawa
sawa

Reputation: 168101

def int_then_float string
  Integer(string)
rescue ArgumentError
  Float(string)
end

Upvotes: 7

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