Updating quantity

Manage cart with update_quantity and remove_item.

In this lesson we'll learn to update the quantity of an item in the cart. Lists are accessed by index; cart[0] is the first item:

cart = ["Apple", "Bread"]
cart[0] = "Apple x2"
print(cart)  # ['Apple x2', 'Bread']

Indexes start at 0. cart[0] = ... replaces the first item. This is the basic way to update list items.

Index access

We access list items by index. Indexes start at 0: cart[0] is the first, cart[1] the second.

cart = ["Apple", "Bread", "Milk"]
print(cart[0])  # Apple
print(cart[2])  # Milk

Negative indexes count from the end: cart[-1] is the last item. This is handy for end checks.

Assign cart = ["Apple", "Bread"]. Update the first item with cart[0] = "Apple x2". Print print(cart).

Show example solution

cart = ["Apple", "Bread"]
cart[0] = "Apple x2"
print(cart)

Update the first item

cart = ["Apple", "Bread"]
cart[____] = "Apple x2"

Show answer

cart = ["Apple", "Bread"]
cart[0] = "Apple x2"