From: Brian Candler <b.candler@...>
Date: 2010-09-03T17:31:17+09:00
Subject: Re: p vs. print

Abder-Rahman Ali wrote:
> When I tried to display the result using
> 
> print ary1
> 
> It did NOT show anything.

print(x) calls x.to_s to get the string representation, then sends that 
to $stdout.

It looks like the object you have returns an empty string or nil from 
its to_s method (which is odd, but you'd have to talk to the author of 
the NArray class about that)

puts(x) is like print(x), but adds a newline if there isn't one at the 
end of the string already.

p(x) is like puts(x.inspect), where x converts an object into a 
debugging string form, that is, one which shows its internal state.

Try this program to see the differences:

class Foo
  def initialize(a)
    @a = a
  end
  def to_s
    "here's a string"
  end
end

f = Foo.new(123)
print f
puts f
p f
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