ruby - can't concatenate array elements into a string?

Question

For personal homework I am trying out a digital clock program to display 'big' numbers.

A ruby program that has parts of the clock that come from strings stored in an array and then a routine (not yet fully written) that can display any numbers as 'big numbers'.
This is to help me learn more about manipulating hashes and iterating through arrays, concatenating string, etc.

I am stuck right now with this:

all_nums=''
(0..3).each do |num|
    all_nums+= (line_parts[num][0].values).to_s
    #puts line_parts[num][0].values
end 
puts all_nums

because I am getting back array elements that I can't convert to strings, i.e.

ruby digital_clock,rb
[" ==  "]["|  | "]["|  | "][" ==  "]

but when I just puts them (commented out 3rd line from the bottom) it is OK but, I get strings, i.e.

ruby digital_clock.rb
 ==  
|  | 
|  | 
 ==

I want to be able to build up the string (big 0 in this case) but I can only puts out the pieces and I've been unable to assign them to a variable and print it. How could I do that?

The full program is:

top=          ' ==      |   ==    ==   |  |   ==   |      ==    ==    == '
top_middle=   '|  |     |   __|   __|  |__|  |__   |__      |  |__|  |__|'
bottom_middle='|  |     |  |        |     |     |  |  |     |  |  |     |'
bottom=       ' ==      |   ==    ==      |   ==    ==      |   ==      |'

number_parts=[{},{},{},{},{},{},{},{},{},{}]
line_parts=[[],[],[],[]]

['top','top_middle','bottom_middle','bottom'].each_with_index do |one_line, i|
  number_parts=[{},{},{},{},{},{},{},{},{},{}]
  (0..9).each do |the_num|
    number_parts[the_num] = {one_line.to_sym => eval(one_line)[the_num*5,5].to_s}
  end
  line_parts[i]= number_parts
end

all_nums=''
(0..3).each do |num|
    all_nums+= (line_parts[num][0].values).to_s
    #puts line_parts[num][0].values
end 
puts all_nums

Don't just give a verbose program, especially if does not work. Tell what you are doing. — sawa
– sawa, Commented Jun 16, 2013 at 13:21
Originally I was going to just give the parts in question but when I do that I usually get told to please show the whole program :) — junky
– junky, Commented Jun 16, 2013 at 13:29

FMc · Accepted Answer · 2013-06-16 15:03:22Z

1

I think this will fix your immediate problem -- namely, printing a big "0".

all_nums = []
(0..3).each do |num|
  all_nums.push(line_parts[num][0].values)
end 
puts all_nums.join("\n")

A better way to do that would be with map:

all_nums = (0..3).map { |num| line_parts[num][0].values }
puts all_nums.join("\n")

Another issue: you don't need to use eval. In fact, one almost never needs to use eval.

# Use variables rather than the strings 'top', 'top_middle', etc.
[top,top_middle,bottom_middle,bottom].each_with_index do |one_line, i|
    ...
    # Then the eval() is unnecessary.
    number_parts[the_num] = {one_line.to_sym => one_line[the_num*5,5]}
    ....

But you can really simplify the code along the following lines:

# Use an array, not a set of specifically named variables.
# This makes it a lot easier to iterate over the data.
rows = [
  '  --     |  --   --  |  |  --  |     --   --   -- ',
  ' |  |    |  __|  __| |__| |__  |__     | |__| |__|',
  ' |  |    | |       |    |    | |  |    | |  |    |',
  '  --     |  --   --     |  --   --     |  --     |',
]

# Create an array-of-arrays.
# num_parts[NUMBER] = [an array of four strings]
width = 5
num_parts = (0..9).map { |n| rows.map { |r| r[n * width, width] } }

# Inspect.
num_parts.each do |np|
  puts
  puts np.join("\n")
end

You might also take a look at the Unix command called banner, which will inspire you to make the numbers EVEN BIGGER. That would allow you to start adding curves and other design touches.

edited Jun 16, 2013 at 15:03

answered Jun 16, 2013 at 14:19

FMc

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1 Comment

junky Over a year ago

+1 Both an answer to my exact problem, plus suggestions on improvements. nice. I wish I could upvote twice. thanks!

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