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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 to output our list for us.
Code Samples
At the end of the video, your code should look like this:
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_list(list)
puts "List: #{list['name']}"
puts "----"
list["items"].each do |item|
puts "Item: " + item['name']
puts "Quantity: " + item['quantity'].to_s
puts "---"
end
end
list = create_list()
puts list.inspect
list['items'].push(add_list_item())
puts list.inspect
print_list(list)
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Okay, so when we last left off,
0:00
we have added onto our shopping list
after calling the add_list_item method.
0:02
And that put list items
into an array of hashes.
0:08
So now that we have all of this done,
let's go ahead and print out our list.
0:14
And we'll create a new method to do that.
0:20
So what I'm gonna do is click up in here
and create a method called print_list.
0:24
And we'll pass in as an argument
the list that we want to print.
0:31
So we know that our list has a name.
0:37
So let's go ahead and
print that out as the first item here.
0:42
Now we do that by using
string interpolation.
0:47
Now we know that the list
name is a string.
0:51
And we access the value of
that by calling list['name'].
0:54
Since it's a string, string
interpolation will work just the same.
1:01
It's just like calling any other variable.
1:06
Now, let's go ahead and create a line.
1:10
That'll just be four dashes.
1:14
Now what we want to do is print
out the items in the list.
1:16
Now we know that the list items
is an array containing hashes.
1:21
What we can do is use
a method called each.
1:27
We'll get into this method a little
bit more in an upcoming course,
1:31
but for right now,
we'll just follow along.
1:34
So we call the method each.
1:40
Now when we call the method each, we use
this new piece of Ruby syntax called
1:42
a block, and then pass in an argument.
1:46
Blocks are written by typing either
curly braces or the words do and end.
1:54
So what this is going to do is take each
item in this array of list items and
2:01
assign it to a variable called item.
2:09
And now, we can print out the item
name and the item quantity.
2:13
Now remember the list items
array is an array of hashes.
2:20
So let's go ahead and
2:25
print out the item['name'] because we want
to know what the name is of the item.
2:27
And we'll also print out quantity and
the item's quantity.
2:34
And then we'll print
out another separator.
2:43
Okay.
2:47
Now that we have this,
let's go ahead and call print_list and
2:48
send in our shopping list.
2:52
Let's run this and see what happens.
2:56
The list name is Groceries,
that item that we're adding is Milk, and
2:58
we're adding one thing of milk.
3:03
Oh, it looks like we
have an error on line 26.
3:07
And the error is, no implicit
conversion of fixnum into String.
3:13
So what we have to do is tell Ruby that
we want this number to be a string.
3:19
And we use the to_s method to do that.
3:25
Let me clear my screen here.
3:27
And we'll run this again and
see what happens.
3:30
Now we're going to add Milk and
one thing of Milk.
3:34
And now here is our grocery list.
3:38
Alright, that looks good, but
3:42
we're going to clean this up
a little bit more in the next video.
3:44
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