Coding for Kids in Python: Create Your First Game with Python by Ellen Tale

Author:Ellen Tale [Tale, Ellen]
Language: eng
Format: azw3, epub
Published: 2020-06-20T16:00:00+00:00

The ‘for’ loop

The ‘for’ loop is a python iterator, just like the while loop. It works on strings, lists, tuples, and dictionaries as well as other built-in objects that can be iterated through

In this lesson, we’ll be learning how to use the ‘for’ loop to solve fundamental mathematics problems and doing other exciting stuff.

Don’t be scared because I mentioned mathematics; you do not need to know a lot of mathematics before you can use the ‘for’ loop.

The generic format of a ‘for’ loop can be seen below.

for target in objects:

statements

Before we proceed to learn more about ‘for’ loops, there is an actual need to know about the ‘break’, ‘continue’ and pass statements

Anywhere you see the ‘break’ statement in a loop or a conditional statement, it is used to terminate or exit that loop or conditional statement

Let’s take an example

for x in range(1,8):

if x == 5:

break

else:

print(x)

The result can be seen below that when x actually became 5, the ‘for’ loop was terminated.

Python 3.8.1 (tags/v3.8.1:1b293b6, Dec 18 2019, 22:39:24) [MSC v.1916 32 bit (Intel)] on win32

Type "help", "copyright", "license()" for more information.

>>>

==================== RESTART: C:\Users\uf\Desktop\new.py =====================

1

2

3

4

>>>

Also, wherever you see the ‘continue’ statement in a loop or conditional statement, it is used to jump to the top or beginning of that loop or conditional statement.

Let’s also take an example here

for x in range(1,8):

if x == 5:

continue

else:

print(x)

It can be seen from the result below that the code jumps the number 5 and proceed to print other numbers.

Note that range(1, 8) is a built-in function which contains number 1 to 7 which could be iterated though using a loop.

Python 3.8.1 (tags/v3.8.1:1b293b6, Dec 18 2019, 22:39:24) [MSC v.1916 32 bit (Intel)] on win32

Type "help", "copyright", "license()" for more information.

>>>

==================== RESTART: C:\Users\uf\Desktop\new.py =====================

1

2

3

4

6

7

>>>

The ‘pass’ statement is often used when there is nothing useful to say or do in a conditional or loop statement. It is commonly used to code an empty body for a compound statement. For example

number = 3

if number == 3:

pass

else:

print ('The number is not 3')

It can be seen from the result below that the code did precisely nothing.

Python 3.8.1 (tags/v3.8.1:1b293b6, Dec 18 2019, 22:39:24) [MSC v.1916 32 bit (Intel)] on win32

Type "help", "copyright", "license()" for more information.

>>>

==================== RESTART: C:\Users\uf\Desktop\new.py =====================

>>>

Let’s take a few practical examples

Let’s try to calculate the mean of different numbers in a list using the ‘for’ loop. I am sure you all remember what a list is and how to use a list and perform different operations using a list from previous lessons.

From our mathematics class in school, do we still remember how to calculate mean? If the answer is No, there is no need to worry, I explain it to you.

In order to calculate the mean of some scores, you have to find out how many scores there are to find the way. Say you have to find the way of these scores, “2, 6, 8, 12, 16, 20, 10, 5, 8, 7”

You count the number of ratings given, and right here, we have 10 scores.

The next step is to add

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