Printf goober

Ruby
1

Hi there!

I was experimenting with printf thus:

puts printf("%s is %d years old.", “booboo”, 12)

and got this result:

booboo is 12 years old.nil

Where does that nil originate and how do I get rid of it?

2

On 27 Jun 2008, at 16:52, Lloyd L. wrote:

I was experimenting with printf thus:

puts printf(“%s is %d years old.”, “booboo”, 12)

and got this result:

booboo is 12 years old.nil

Where does that nil originate and how do I get rid of it?

Your code contains two expressions:

puts (printf(“%s is %d years old.”, “booboo”, 12))

so the printf is outputting the string “Booboo is 12 years old.” and
returning the value nil,
then puts is outputting that nil

Ellie

Eleanor McHugh
Games With Brains
http://slides.games-with-brains.net

raise ArgumentError unless @reality.responds_to? :reason

3

perhaps you’re thinking of sprintf?

printf returns nil, but displays the string to the screen, so what’s
happening here is
puts(printf(“blah.”))

printf prints out “blah.” without a return, then puts prints out the
return value of printf, which is nil.

so you get

blah.nil

To do what you want, use sprintf, which returns for the formatted string

–Kyle

4

Perfect! Thanks!

5

It turns out that I mixed the

printf("%s is %d years old.", “booboo”, 12)

with

puts “%s is %d years old.” % [“booboo”, 12]

doh!