Step 4 - Learn Variables in Python

Theory

What is the variable?

Objects (text, numbers, complex data structures) with data are stored inside computer memory.
In the real world we use a post address when we need to visit some place or a building.
Computers also use addresses to get access to a particular object in memory and it looks like this 0x00000284DE5A3E20
A variable is simply a name you give to a memory address where an object is stored.
It’s much simpler to remember that your data is located in a variable with name data rather than 0x00000284DE5A3E20

We use the equals sign “=” between variable name and an object we want to give this name to.

Let’s now use a variable in our first ‘hello world’ program, for now we simply give it the name “my_variable”.

  
my_variable = "hello world"
print(my_variable)

Here is what happens:

We create a new variable and assign a string data to it.
The print statement looks what memory address variable represents.
The print statement then fetches the text data in that memory location and outputs it into the terminal.

Python Print function with variable example visualized

Let’s also modify ‘enter your name’ program and use a variable to store the data a user enters:

  
your_name = input("enter your name: ")
print(your_name)

Here is what happens:

We create a new variable your_name
input("enter your name: ") asks user to enter name in the Terminal.
As soon as user enters it and hits Enter key, input() sends this text to the your_name variable.
The user’s name is now stored inside this variable.
The print statement then fetches the text data stored in an address represented by your_name and outputs it into the terminal.

Python Print and Input functions function with variable example visualized

When a user enters their name it’s going to be stored as string.

Let’s now start writing our calculator.

Re-use the code we wrote in the previous Step
We want a user to enter two numbers and then print them in the terminal.
Create first variable which will represent first number and read this data from the Terminal using input() function.
Similarly, create second variable which will represent second number and read this data from the Terminal.
Print both numbers using one print statement.

The result should look like this:

  
enter first number: 70
enter second number: 7
70 7

  
number_1 = input('enter first number: ')
number_2 = input('enter second number: ')
print(number_1, number_2)