Iterative Functions

In the For Loops section in Chapter 1, Vital Python – 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)

You should get the following output:

0
1
2
3
4

For loops can also be placed within functions.

Exercise 48: 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:

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
       return result
    ...