14. For loops using the range function

See: https://www.w3schools.com/python/python_for_loops.asp

To loop through a set of code a specified number of times, use the range() function.
The range() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and ends at a specified number.

14.1. Range function starting at 0

range(stop_value)

Returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and ends before the stop_value number.

range(3) returns the numbers 0, 1, 2. It starts at 0. It goes up by 1. It stops before 3, at 2.
The code below will display the numbers from 0 to 2.
from microbit import *

while True:
    for n in range(3):
        display.scroll(n, delay=80)
    sleep(500)

Tasks

  1. Using the range function, write a for-loop that displays the numbers from 0 to 5.

  2. Using the range function, write a for-loop that displays the numbers from 0 up to but not including 10.

Using the range function, write a for-loop that displays the numbers from 0 to 5.

from microbit import *

while True:
    for n in range(6):
        display.scroll(n, delay=80)
    sleep(500)

Using the range function, write a for-loop that displays the numbers from 0 up to but not including 10.

from microbit import *

while True:
    for n in range(10):
        display.scroll(n, delay=80)
    sleep(500)

14.2. Range function with start and stop values

range(start_value, stop_value)

Returns a sequence of numbers, starting at the start_value number, and increments by 1 (by default), and ends before the stop_value number.

range(2, 6) returns the numbers 2, 3, 4, 5. It starts at 2. It goes up by 1. It stops before 6, at 5.
range(2, 6) can be read as ‘range of 2 up to but not including 6’.
The code below will display the numbers 2, 3, 4, 5.
from microbit import *

while True:
    for n in range(2, 6):
        display.scroll(n, delay=80)
    sleep(500)

Tasks

  1. Using the range function, write a for-loop that displays the numbers 3, 4, 5, 6, 7.

  2. Using the range function, write a for-loop that displays the numbers from 4 up to but not including 9.

Using the range function, write a for-loop that displays the numbers 3, 4, 5, 6, 7.

from microbit import *

while True:
    for n in range(3, 8):
        display.scroll(n, delay=80)
    sleep(500)

Using the range function, write a for-loop that displays the numbers from 4 up to but not including 9.

from microbit import *

while True:
    for n in range(4, 9):
        display.scroll(n, delay=80)
    sleep(500)

14.3. Range function with a step size

range(start_value, stop_value, step_size)

Returns a sequence of numbers, starting at the start_value number, incremented by step_size, and ending before the stop_value number.

range(1, 6, 2) returns the numbers 1, 3, 5. It starts at 1. It goes up by 2. It stops before 6, at 5.
range(1, 6, 2) can be read as ‘range of 1 up to but not including 6 in steps of 2’.
The code below will display the numbers 1, 3, 5.
from microbit import *

while True:
    for n in range(1, 6, 2):
        display.scroll(n, delay=50)
    sleep(500)

Tasks

  1. Using the range function, write a for-loop that displays the numbers 2, 4, 6, 8.

  2. Using the range function, write a for-loop that displays the numbers 3, 7, 11, 15.

Using the range function, write a for-loop that displays the numbers 2, 4, 6, 8.

from microbit import *

while True:
    for n in range(2, 9, 2):
        display.scroll(n, delay=50)
    sleep(500)

Using the range function, write a for-loop that displays the numbers 3, 7, 11, 15.

from microbit import *

while True:
    for n in range(3, 16, 4):
        display.scroll(n, delay=50)
    sleep(500)

14.4. Using range to count down with a negative step size

range(10, 0, -1) counts down from 10 to 1.
from microbit import *

while True:
    for n in range(10, 0, -1):
        display.scroll(n, delay=80)
    sleep(500)

Tasks

  1. Using the range function, write a for-loop that displays the numbers 9, 7, 5, 3.

  2. Using the range function, write a for-loop that displays the numbers 8, 5, 2.

Using the range function, write a for-loop that displays the numbers 9, 7, 5, 3.

from microbit import *

while True:
    for n in range(9, 2, -2):
        display.scroll(n, delay=80)
    sleep(500)

Using the range function, write a for-loop that displays the numbers 8, 5, 2.

from microbit import *

while True:
    for n in range(8, 1, -3):
        display.scroll(n, delay=80)
    sleep(500)