How can I check if a value is a number?

Question

I want to simply check if a returned value from a form text field is a number i.e.: 12 , 12.5 or 12.75. Is there a simple way to check this, especially if the value is pulled as a param?

Answer 1

You can use

12.is_a? Numeric 

(Numeric will work for integers and floats.)

If it arrives as a string that might contain a representation of a valid number, you could use

class String   def valid_float?     true if Float self rescue false   end end 

and then '12'.valid_float? will return true if you can convert the string to a valid float (e.g. with to_f).

Answer 2

I usually just use Integer and Float these days.

1.9.2p320 :001 > foo = "343"  => "343" 1.9.2p320 :003 > goo = "fg5"  => "fg5"  1.9.2p320 :002 > Integer(foo) rescue nil  => 343 1.9.2p320 :004 > Integer(goo) rescue nil  => nil  1.9.2p320 :005 > Float(foo) rescue nil  => 343.0 1.9.2p320 :006 > Float(goo) rescue nil  => nil