Variable Assignments in Python

This blog post is part of our course Python Tutorial for Ultimate Beginners.

Now that we’ve seen how to use numbers in Python as a calculator let’s see how we can assign names and create variables.

We use a single equals sign to assign labels to variables. Let’s see a few examples of how we can do this.

# Let's create an object called "a" and assign it the number 
5 >>> a = 5

Now if I call in my Python script, Python will treat it as the number 5.

# Adding the objects
>>> a+a 
10

What happens on reassignment? Will Python let us write it over?

# Reassignment 
>>> a = 10 
# Check 
>>> print(a) 
10

Rules for variable names

• names can not start with a number
• names can not contain spaces, use _ instead
• names can not contain any of these symbols as :'",<>/?|!@#%^&*~-+
• it’s considered best practice (PEP8) that names are lowercase with underscores
• avoid using Python built-in keywords like list and str
• avoid using the single characters l (lowercase letter el), O (uppercase letter oh) and I (uppercase letter eye) as they can be confused with 1 and 0.

Dynamic Typing

Python uses dynamic typing, meaning you can reassign variables to different data types. This makes Python very flexible in assigning data types; it differs from other languages that are statically typed.

>>> my_dogs = 2 
>>> print(my_dogs) 
2
>>> my_dogs = ['Sammy', 'Frankie'] 
>>> print(my_dogs) 
['Sammy', 'Frankie']

Determining variable type with type()

You can check what type of object is assigned to a variable using Python’s built-in type() function. Common data types include:

>>> a = 2 
>>> print(type(a)) 
int

Originally published at https://blog.upendra.tech on June 3, 2020.