Iterative functions

In the For loops section of Chapter 1, Python Fundamentals – Math, Strings, Conditionals, and Loops, you were introduced to the syntax for looping over objects in Python. As a refresher, here is an example where you perform five iterations and print the i variable in each loop:

for i in range(5):
    print(i)

The output is as follows:

0
1
2
3
4

For loops can also be placed within functions.

Exercise 49 – a simple function with a for loop

In this exercise, you create a sum_first_n function that sums up the first n integers. For example, if you pass the n=3 function, it should return 1 + 2 + 3 = 6. Let’s see the steps:

1. In a Python shell, enter the function definition. Note that the tab spacing needs to match the following output:

   def sum_first_n(n):

       result = 0

       for i in range(n):

           result += i + 1

     &...