Build a Grocery List Program: Part 4

4:17 with Jason Seifer

Now that we know how to use arrays and hashes, we're going to build a small program that makes a grocery list for us. In this video, we'll clean up and put the finishing touches on our grocery list program.

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Here is our finished program:

def create_list
  print "What is the list name? "
  name = gets.chomp

  hash = { "name" => name, "items" => Array.new }
  return hash
end

def add_list_item
  print "What is the item called? "
  item_name = gets.chomp

  print "How much? "
  quantity = gets.chomp.to_i

  hash = { "name" => item_name, "quantity" => quantity }
  return hash
end

def print_separator(character="-")
  puts character * 80
end

def print_list(list)
  puts "List: #{list['name']}"
  print_separator()

  list["items"].each do |item|
    puts "\tItem: " + item['name'] + "\t\t\t" +
         "Quantity: " + item['quantity'].to_s
  end

  print_separator()
end

list = create_list()

puts "Great! Add some items to your list."

list['items'].push(add_list_item())
list['items'].push(add_list_item())
list['items'].push(add_list_item())

puts "Here's your list:\n"
print_list(list)

0:00
So when we last left off, we had printed out our list.
0:05
And let's go ahead and run this again.
0:08
The item is milk and we only want one thing of milk.
0:11
Okay, let's clean up how this looks a little bit.
0:15
First, since we're sort of duplicating code here,
0:19
by printing out a separator, let's go ahead and make a method out of that.
0:24
And we'll call that method output_separator.
0:31
You know what? Let's call it print_separator.
0:34
And we'll give it an argument of the character that we wanna print.
0:39
And we can go ahead and give this a default value of a dash.
0:46
And all this method is going to do is print that character 80 times.
0:55
Now let's go ahead and
0:56
replace the printing of the separator with the method name.
1:06
Okay.
1:09
Clear my screen here and run this again.
1:13
You know what I can take out the list here.
1:16
I can take out the list inspection since we're printing it on our own now.
1:21
This name is Groceries, and the item that we're adding is milk.
1:26
And 1.
1:27
Okay, now we have a separator.
1:31
But let's go ahead and clean this up even a little bit more.
1:35
So now let's go ahead and indent each line here.
1:38
So we'll print a tab character Inside of this list and
1:43
the item's name and then another plus.
1:46
And let's say we'll do three tab characters here and the quantity.
1:51
Now I want quantity to be all on the same line so
1:55
I'm going to add another plus and take out that put statement.
2:03
And this will create one big string and
2:06
send it in as an argument to the puts method.
2:09
Let me clear my screen here, click in to the console and run this again.
2:20
Okay, this is looking a little bit better.
2:22
We've got our grocery list, and our item of milk, and our quantity of one.
2:28
Let's go ahead and say that we want to add another list item.
2:34
Print my screen and run this again.
2:35
List name is groceries.
2:38
The item is milk, and we only want one.
2:40
Bread, we're gonna say we want two loaves of bread.
2:43
And that looks good.
2:44
We've got a separator in between each of the items.
2:48
But you know what?
2:49
Let's go ahead and print the separator at the end of all the list items instead.
2:53
I think that'll look just a little bit better.
3:00
And now let's go ahead and just add another item to the list.
3:05
And in fact before we print the list, I'm just going to print here's your list.
3:13
And a new line.
3:16
In fact let's go ahead and add another message and say great.
3:20
Add some items to your list.
3:25
Now let me clear my screen here, there's gonna be more output so
3:28
I'm gonna make this a little bit bigger and type ruby.shoppinglist.rb.
3:35
This name is groceries Great.
3:37
Let's add some items to the list.
3:40
Milk, we only need one.
3:42
Bread, two loaves of bread.
3:45
Eggs, let's get three dozen eggs because we're really hungry.
3:50
All right, and here is our grocery list with our three different items and
3:55
the corresponding quantities.
3:58
In this course, we've learned about how arrays and hashes work, and
4:02
have even learned some simple iteration.
4:05
Don't stop now, though.
4:07
Make sure to practice these concepts on your own, and
4:10
practice by building your own programs.
4:12
If you need inspiration, check out the extra credit.
4:16
Happy coding.

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