On Mon, Aug 24, 2009 at 3:57 AM, Scott Andrechek
[email protected]wrote:
tableZ=0
thisisthetitle.push toptitle
puts table[tableZZZ]
linewidth4=5
if tableZ==0
-Scott Andrechek
Posted via http://www.ruby-forum.com/.
Hi, Scott,
The ruby syntax is
if
elsif
else
end
In your example, you did
if toptitle==‘’
if toptitle !=‘’
end
end
So you were actually nesting if statements. However the inner if
statement
was guaranteed to never be true, because it was the negation of the
first if
statement. What you could do instead is
if toptitle == ‘’
else #by default, this means that toptitle!=‘’
end
I refactored the code a bit (I tried not to vary too much from your
format).
There were some places that were getting a little bit convoluted,
keeping
track of lots of counters, and incrementing / decrementing them as you
went
through the array. There were also some variables that I thought would
be
better off being a different type. I renamed some variables to follow
more
rubyish conventions.
get the table title
puts ‘Please type the title for your table (if you type nothing the
title
will be Table of Contents)’
table_title = gets.chomp # not really any need to put this variable
into an
array
table_title = ‘Table of Contents’ if table_title.empty? #empty string
will
return true
get the chapter titles, place them into the array
split turns our string into an array, it uses a comma for a delimiter
because I passed it
a comma in a string.
map! just loops through each element in the array, and replaces the
array
element with
the last line of the submitted block.
the ! indicates that it does it to the array we are calling it on.
Without the !, it would
return a new array with those elements
the |t| says that we want to access the current element (a title)
through a variable named t
strip removes leading and tailing whitespace from a string
documentation for split
http://www.ruby-doc.org/core/classes/String.html#M000803
documentation for map!
http://www.ruby-doc.org/core/classes/Array.html#M002190
documentation for strip
http://www.ruby-doc.org/core/classes/String.html#M000820
puts ‘Please type your titles in one line, separated by commas.’
table = gets.split(‘,’).map!{|t| t.strip} # so this could be expressed
in
English as “get the next line,
# split it into an array of
titles, and replace each title in
# the array with the same
title,
after whitespace has been removed”
# this is also why we don’t
have
to say gets.chomp, because \n is whitespace
get the page numbers
replace the chapter titles with an array containing the chapter title,
and
the page number
note that map!{…} and map do … end can both be used,
I usually use {} for single line blocks, and do end for multi line
blocks
puts ‘Please type your page numbers’
table.map! do |chapter_title|
print "The page number for " + chapter_title.inspect + " should be: "
[chapter_title , gets.chomp]
end
initializations for printing out the table
I think a hash makes a lot of sense here, because you were having to
remember that specific numbers
correllate to specific places to use the line widths, if we use a
hash, we
can essentially label which
values are which. For our keys, we use symbols, these are similar to
strings, but they all point to
the same object. (you could replace them with strings if it made you
feel
more comfortable)
documentation for Symbol
http://www.ruby-doc.org/core/classes/Symbol.html
line_widths = { :table_title => 45 ,
:chapter_title => 60 ,
:word_page => 10 ,
:page_number => 5 }
word_page = ‘page’ # not really any need for this variable to be an
array
print out the table title
puts
puts table_title.rjust( line_widths[:table_title] ) #pull the
appropriate
width from the hash, notice how
#much it looks like
accessing an index in an array
print out the table
here we use the each method, which loops through each element in the
array
we pass it a block by using do |parameters| … end
in this case, we are receiving one parameter, the array [chapter_title
,
page_number]
this was set back when we took the page numbers
we can group our parameters together with () so that this ultimately
becomes
chapter_title , page_number = [ “some chapter title” , “12” ]
which is a common Ruby way of assigning values, try it out if you
like.
table.each do |(chapter_title,page_number)|
#when the argument is the last thing on the line, you don’t actually
need
parentheses
print chapter_title.ljust line_widths[ :chapter_title ]
print word_page.rjust line_widths[ :word_page ]
puts page_number.rjust line_widths[ :page_number ]
end
puts
puts ‘Table Created by Table MakerTM’
now, for some real fun, you should try turning it into a class 
