Regex to check alphanumeric string in ruby

Question

I am trying to validate strings in ruby. Any string which contains spaces,under scores or any special char should fail validation. The valid string should contain only chars a-z

Answer 1

def alpha_numeric?(char)  

   if((char =~ /[[:alpha:]]) || (char =~ [[:digits:]]))
      true
   else
      false
   end

end

OR

def alpha_numeric?(char)  

   if(char =~ /[[:alnum:]])
      true
   else
      false
   end

end

We are using regular expressions that match letters & digits:

The above [[:alpha:]] ,[[:digit:]] and [[:alnum:]] are POSIX bracket expressions, and they have the advantage of matching unicode characters in their category.Hope this helps helps.

checkout the link below for more options: Ruby: How to find out if a character is a letter or a digit?