Example 1: Why do we need loops?

Assume you need to print all integers from 1 to 99. Without a loop this takes 99 print statements:


If tomorrow we want print the numbers from 1 to 200, we would need to add 101 print statements to the code!

A loop – in this case a for-loop – gives us an abstraction leading to flexibility. We need to change only one number to vary the number of integers printed:

for number  in range(1,100):


# 02Loops example_01 WhyLoops.py
last_number  = 99
for number  in range(1,last_number+1):

The range function is the most commonly used construct in for-loops. The following video gives a brief review/refresher on the various ways we can use range to generate a sequence of integers to iterate over. Video Length: 4:18