Listing tasks

Print tasks with list_tasks.

Listing tasks (list_tasks)

Let us write a list_tasks function to list the added tasks. With enumerate we get both the index and the value:

def list_tasks():
    for i, t in enumerate(tasks):
        print(i, t)

This shows tasks numbered: 0 Buy bread, 1 Buy milk. The index will be used later for completing tasks.

How enumerate works

enumerate(tasks) yields a (index, value) pair at each loop:

for i, t in enumerate(["Bread", "Milk"]):
    print(i, t)
# 0 Bread
# 1 Milk

This is more Pythonic than a classic range(len(tasks)) loop. It is ideal for accessing index and value at once.

This is a very common pattern in Python.

Exercise Add the list_tasks function

Define a function called list_tasks with no parameters. In the body build a loop for i, t in enumerate(tasks): and do print(i, t). Call it with list_tasks().

Show example solution

def list_tasks():
    for i, t in enumerate(tasks):
        print(i, t)
list_tasks()

Test yourself

Complete the list_tasks body

def list_tasks():
    for i, t in ____(tasks):
        print(i, t)

Show answer

def list_tasks():
    for i, t in enumerate(tasks):
        print(i, t)

What does list(enumerate(["a", "b"])) return?
- ["a", "b"]
- [0, 1]
- [(0, "a"), (1, "b")]
- [("a", 0), ("b", 1)]
Show answer

[(0, "a"), (1, "b")] — enumerate yields (index, value) pairs.
Match the listing parts

enumerate

Index and value
for i, t in

Loop shape
print(i, t)

Print
list_tasks()

Call

Next lesson: Completing tasks

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