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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 modify our program make use of the methods we've written.
Code Samples
Here's what our code looks like now:
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
list = create_list()
puts list.inspect
list['items'].push(add_list_item())
puts list.inspect
So when we just left off we had created a shopping list and 0:00 printed out the contents. 0:03 Now let's go ahead and add on to this and add an item to this list. 0:05 So let's go ahead and call add list item dot inspect, and 0:11 what that's gonna do is the call the add list item method and 0:15 then we're just gonna see what the output is first. 0:20 So we click down into the console and type rubyshoppinglist.rb. 0:26 The list name is groceries, and we don't have any items, so let's go ahead and 0:30 add an item. 0:34 And the item is milk. 0:35 Uh-oh. 0:38 Undefined local variable or method name for main object. 0:39 That's because we spelled it wrong. 0:44 Our program freaked out a little bit, and that's okay. 0:47 It exited, but nothing catastrophic happened. 0:51 So let's go ahead and clear the screen, and run that again. 0:53 And actually, let's put a space here, format that just a little bit better. 0:56 List name is Groceries, and go ahead and add milk to our grocery list. 1:01 And we can see that we return a new hash with the key of name, 1:06 and the value of milk. 1:12 And that's okay, but what I think I would like to do is also get the quantity back. 1:15 So let's go ahead and ask how much. 1:22 And we'll get from standard input again, and 1:28 then call to I on that, which will turn it into a number. 1:32 And now we'll put that into the hash. 1:40 Now let's go ahead and run this again and see what happens. 1:44 List name is Groceries. 1:48 Item is milk. 1:51 And I only want one. 1:53 Now we can see that this add list item method is returning a hash with two keys, 1:56 name and quantity. 2:01 Now let's go ahead and take a look at our list and see how it looks. 2:04 Gonna clear my screen here and run the program again. 2:10 So here is the item that we're returning, but 2:19 it's not being added to our list of items inside of the hash. 2:22 So let's go ahead and fix that. 2:29 What we're gonna do is use the push method and the reason is items is an array. 2:32 So let's go ahead and type list.push, and 2:40 then the argument that we're adding to push is add list item. 2:44 Now, we can print out the contents of the list again. 2:54 Let me clear my screen here and run it again. 3:01 Okay, we've got our grocery list created, milk, and we only need one. 3:05 Uh-oh, undefined method push for this hash. 3:12 Now what could that be? 3:17 Well, we're not pushing onto the list hash. 3:20 We're pushing onto the list items inside of the hash. 3:24 Now let's clear this and run it again. 3:31 Okay. 3:38 Now this is what our grocery list looks like. 3:40 It's a hash with two keys, name which is Groceries, 3:43 items, which is an array, which contains a hash. 3:49 In our next video we're going to format this. 3:55
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