Makerspace

A for loop iterates over a list (or other sequence) and executes a block of code, once for each item in the list. Recall the while loop we wrote earlier:

x = 1
while x <= 5:
  print(x)
  x = x + 1

We can do the same thing in only two lines of code using a for loop along with the range function:

for x in range(1,6):
  print(x)

Output:

1
2
3
4
5

The range function returns a sequence of numbers, starting at 0 (by default), incrementing by 1 (by default), and stopping at the end number. The example above passes in both the start and stop numbers as parameters. Here’s an example that passes in just the stop number (using the default start number of 0):

for x in range(4):
  print(x)

Output:

0
1
2
3

Here’s an example of a for loop iterating over our grocery list:

groceries = ['eggs', 'milk', 'bread', 'coffee']
for g in groceries:
    print(g)

Output:

eggs
milk
bread
coffee

Exercises

Modify the last example above to print out a numbered grocery list. For example:

1. eggs
2. milk
3. bread
4. coffee

Hint: use the len and range functions, and start your list at “1.”, not “0.”