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Learning Python – Lesson 3: Introducing Variables

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We all know that variables are a key part of programming and scripting languages, and sure enough, they are a big part of Python. Here is how simple they are to implement:

#Today we are going to create and use some variables! 
#This is really cool! 
#Hey just to remind you, these are comments that are here to make our code "self-documenting"! 
#Python itself is ignoring the s#$t out of these! 
my_books = 14
my_years_on_planet = 47
books_per_year_on_planet = my_books / my_years_on_planet
print ("Below is my books per year on the planet!")
print (books_per_year_on_planet)

Notice here I am using Python 3 so I need parenthesis around the objects and text that I want to print instead of the older quotation marks! This is the most noticeable difference between Python version 2 and version 3. The PRINT function got a nice little update in this regard.

Here is the result of my program!

Python 3.6.0 (v3.6.0:41df79263a11, Dec 23 2016, 07:18:10) [MSC v.1900 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> 
======================= RESTART: C:\Users\terry\ex3.ps =======================
Below is my books per year on the planet!
0.2978723404255319

>>>
If you are you are using Python 2, you need the “older” syntax to make those print functions work right. Here is that version of our code for you:

#Today we are going to create and use some variables! 
#This is really cool! 
#Hey just to remind you, these are comments that are here to make our code "self-documenting"! 
#Python itself is ignoring the s#$t out of these! 
my_books = 14.0
my_years_on_planet = 47.0
books_per_year_on_planet = my_books / my_years_on_planet 
print "Below is my books per year on the planet!" 
print books_per_year_on_planet

Notice another change here – I need to indicate my variables are of the Float type in order to display my result in the format I need. So I enter my 14.0 and 47.0 for the variable values. I will discuss this in greater detail in the next post!

One final note, if you wanted to use the print function so that it would work in both version 2 and version 3, you would want to use both the ( and the ” as I did in the first program above. For example, I am using Python 2 now:

print ("Hello World!")

This returns:

Hello World!

just as it would in Python 3.

Remember, free Python training is waiting for you at CBT Nuggets!