PythonLesson 7 of 16

for loops and range() in Python

A for loop walks through a list and does the same thing for each item. Three tracks or three thousand, the code stays just as short.

Key points

for x in my_list: gives x each value in turn
range(5) gives 0, 1, 2, 3, 4; range(1, 6) gives 1 to 5
A third argument is the step: range(3, 0, -1) counts down
total += price is short for total = total + price
range(len(items)) gives indexes, handy for walking two lists together

Example

playlist = ["Intro", "Sunrise", "Run"]for song in playlist:    print("Playing", song) for n in range(3, 0, -1):    print(n)print("Go!")

The indented lines are the loop body and repeat each time. print("Go!") has no indent, so it runs once, after the loop.

Task

How to use the editor⌘ Enter or Ctrl Enter runs the code, ⇧ ⌘ Enter checks the task.Tab and Shift Tab indent the line or the selection; Esc, then Tab leaves the editor.The check compares what the program printed with the task; spaces at line ends do not matter.After two failed checks you may open the solution. Your code is kept in this browser.

Print the receipt: each item as 1. tea - 150 (numbered from one), then the total after the loop. Collect the sum in total.

items = ["tea", "cake", "juice"]prices = [150, 220, 180]total = 0for i in range(len(items)):    # TODO: print a line like "1. tea - 150" and add the price to total    passprint("Total:", total)

items = ["tea", "cake", "juice"]
prices = [150, 220, 180]
total = 0
for i in range(len(items)):
    # TODO: print a line like "1. tea - 150" and add the price to total
    pass
print("Total:", total)

Output

What your program prints appears here.