Our programs are executed 1 instruction at a time from top to bottom:

First instruction
Second instruction
Third instruction

Modify this program so that it counts to 3:

Repeating ourselves a fixed number of times is tedious

for

for loops provide a way to iterate over a series of items (formally an Iterable in Python)

for structure

for variable in iterable:
    # loop body executed for each item in iterable

for structure details

• The variable name will be bound for use in the loop body and will reference the item currently being iterated over.
• Both the colon on the first line and the indentation on the second are required for this to be valid Python code.

Alter this program to count from 0 to 5

range

• range generates items to iterate over in Python
• We can change it’s behavior in various ways

Simple range

range(stop)

• In it’s simplest form, range counts up from 0 until it has returned stop items.
• Note that this means that range(3) will count from 0 to 2 (0,1,2).

Advanced Range

range(start, stop, step)

• We can also control the starting number and step size for range.
• To count to 12 by 3s, we might use range(0,13,3)

Alter this program to count from 10 to 50 by 10s