From: "David A. Black" <dblack@...>
Date: 2009-07-17T09:04:21+09:00
Subject: Re: Need Help with a Very, Very Simple Program

Hi --

On Fri, 17 Jul 2009, Max Norman wrote:

> I'm almost an absolute novice in Ruby; it is my first language and I
> just began learning the basics yesterday, using Chris Pine's 'Learning
> to Program.'

Welcome to Ruby!

> The trouble I'm having is simple, but nonetheless I would appreciate an
> explanation. The little program I've written accomplishes a simple task:
> it asks for your favorite number, adds one to it, then returns it to
> you. Here it is:
>
> puts 'Hey there, I\'m Uno.'
> puts 'What\'s your favorite number?'
> number = gets.chomp
> better = number.to_i + 1
> puts better + '...That\'s better.'
>
> I'm receiving this error: String can't be coerced into Fixnum
> (TypeError).' Why can't this variable--which contains a numeric
> string--be converted into an integer?

The reason is that better is an integer, but "That's better." is a
string. So it's like you're trying to do:

   5 + "hello"

and that doesn't work. You can convert back:

   puts better.to_s + "...That's better"

or use Ruby's string interpolation syntax, which inserts expressions
into strings, via the #{} construct, and does the conversion for you:

   puts "#{better}...That's better."

I've interpolated better, not better.to_s, and it will automatically
be to_s'd for me.


David

-- 
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