From: Xavier Noria <fxn@...>
Date: 2007-02-19T22:03:06+09:00
Subject: Re: return statement

On Feb 19, 2007, at 1:44 PM, Derek Teixeira wrote:

> i've been getting confused about what exactly the return statement
> does...

Return means "we are done".

Sometimes when you write a method (I don't know the jargon used in  
that book, it may be function, or subroutine, or procedure, ...) you  
know somewhere in the middle that _if the code reached that point_ we  
do not need to do anything else. For instance, see this method that  
says where the given number is positive:

   def is_positive?(n)
     if n > 0
       return true
     end
     return false
   end

That method can be written in different ways, but to depict the  
meaning of return: if n is greater than 0, you already know the  
answer, so in that point you indicate there's no need to execute more  
code, you're ready to give the answer: true. If the execution reaches  
that point, the following executable line "return false" will be  
ignored altogether, execution is halted.

Return in addition accepts a value to be returned (true/false in the  
example), which is considered to be the _result_ of that method call  
in such case.

> Along with that confusion on the return function.. i was code tracing
> the code below and i understand it, except for one part, i just don't
> see where the code tells the program to print out the numString. I see
> it telling the program to in the 'one hundred' section, but not at all
> in the teens or single digits?

> def englishNumber number

<snip>

> end

The purpose of that method is to compute and return a _string_, not  
to actually _print_ that string.

> puts englishNumber(  0)

Now here you have two calls: first a call to englishNumber(  0), and  
then a call to puts. They are executed in that order, and the string  
returned by the first call is chained into the second call, so puts  
is the one that prints the string.

Does that help? Please do no hesitate to send more questions.

-- fxn