Ruby : Convert String to Float

Question

I have 3 string variables that I need to add. a = "5.21", b= "5.22" and c = "5.23". When I try to add i get a string, I need the numerical value

I have tried the following

a = a.to_f => 5.2
b = b.to_f => 5.2
c = c.to_f => 5.2
sum = a + b + c => 15.6

How do i get output 15.66. please help

Are you sure your a, b and c parameters are not all set to "5.2"? ... seems like the #to_f method should return a different value. Maybe the values are changed by some line of code you didn't notice...? — Myst
– Myst, Commented Apr 13, 2015 at 0:18
I suspect you have one or more invisible characters in your strings. Try this and report the result: .each_char { |c| puts c.ord }. Where did the values of a, b and c come from? — Cary Swoveland
– Cary Swoveland, Commented Apr 13, 2015 at 1:33

garythegoat · Accepted Answer · 2015-04-13 01:10:50Z

11

Try taking advantage of Ruby's built in Enumerable methods. Try this:

a = "5.21"
b = "5.22"
c = "5.23"

[a, b, c].map(&:to_f).inject(:+)
#=> 15.66

edited Apr 13, 2015 at 1:10

answered Apr 12, 2015 at 22:38

garythegoat

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4 Comments

napsterdsilva Over a year ago

i am using 2.0.0 and i am getting 15.6 using the above solution

garythegoat Over a year ago

Are you sure there's no other code modifying these variables? Also, are their values the same as the strings you gave? If there are other, non-Numeric characters in the string it can have unintended behavior. See ruby-doc.org/core-2.2.0/String.html#method-i-to_f

napsterdsilva Over a year ago

I am reading this value from an android app Once i read the value from the app, just to makes sure its a string i am calling the a = a.to_s.strip methods. then a = a.to_f. This still returns jus 5.0 although in this case the string was 5.00

garythegoat Over a year ago

Try printing a at each step in the process, including before you call to_s.strip on the number. If at some point you start seeing a with only one number after the decimal, you know the previous operation cut it off. Let me know what happens.

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