Comments on: Ruby strings and is_int?

By: Fred Bruneteau

Fred Bruneteau — Mon, 14 Apr 2008 13:51:08 +0000

The Robin’s tip is interesting because it’s realy test the numeric value.
Be careful of the method to_i( ) of the class String, I have detected this behaviour :
irb > "47azerty".to_i => 47 irb >
The method to_i( ) only used the digits at the beginning of the string.

N.B. : I use Ruby 1.8.6

By: Matt Berther

Matt Berther — Thu, 03 Apr 2008 17:19:44 +0000

@rik: I think I need to spend more time in IRC and some more time with Ruby in general. I think the point of my post was that I was just surprised that this was not available in Ruby already. Your method for doing this is exactly the same as I would do it in my .NET projects.

By: Rik Hemsley

Rik Hemsley — Thu, 03 Apr 2008 07:49:53 +0000

Converting a string to an integer is FAQ #1 on IRC.

The usual answer given is:

Integer(s) rescue default

… where default is whatever you want the result to be if s won’t convert to an Integer.

By: Matt Berther

Matt Berther — Thu, 03 Apr 2008 04:53:06 +0000

@robin: thanks for the tips. I actually prefer the first, since I dont end up monkey-patching the string class unnecessarily. I also found that I need to validate my page parameter for nil as well, so the line looks like this:

page = “1″ if not page.nil? and page.to_i < 1

By: Robin Curry

Robin Curry — Thu, 03 Apr 2008 04:50:55 +0000

Ha, here’s another way to do it (can’t take credit for this, I found it somewhere else):

def is_int? self.to_i.to_s == self end

By: Robin Curry

Robin Curry — Thu, 03 Apr 2008 04:42:59 +0000

to_i will convert a non-numeric string value to 0, so you could do something like:

page = “1″ if page.to_i < 1