Variables in Python

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Welcome to the series of python language tutorials. We will cover basic to advance level usage of language. I will explain each topic in detail and try to make some exercises at the end of each topic. Python language is very high in demand.

In this tutorial, I will cover Variables in Python

Variables

Creating variables in python is very easy. There is no such common set of protocols that you have to follow to declare the variable.

x = 10
y = "Abdul"
print(x)
print(y)
This will print
10
Abdul

The variable type can be changed easily even if it is declared earlier.

x = 5   # x is of type int
x = "Basit" # x is now of type str
print(x)
The above line prints
Basit

Let me explain the above snippet of code.
In the first line, the value of x is 5 and the type is Int
In the Second line, the value is updated and Now X is storing “ Basit” which is the type of Str. So when I call the Print function and pass the variable X it prints “Basit”

Casting

Casting is the process in which you specify the type of the variable

x = str(6)    # x will be '6'
y = int(6)    # y will be 6
z = float(6)  # z will be 6.0

If you want to check the type of the variable you can use the built-in function call type()

x = 5
y = "Jack"
print(type(x))
print(type(y))
The output of these two print functions will be like this
int
str

There are some rules for naming the python variables.

A variable can have a short name (like x and y) or a more descriptive name (age, surname, total_volume). Rules for Python variables:

• A variable name must start with a letter or the underscore character
• A variable name cannot start with a number
• A variable name can only contain alpha-numeric characters and underscores (A-z, 0–9, and _ )
• Variable names are case-sensitive (age, Age, and AGE are three different variables)

myvar = "Abdul"
my_var = "Abdul"
_my_var = "Abul"
myVar = "Abul"
MYVAR = "Abul"
myvar2 = "Abul"
print(myvar)
print(my_var)
print(_my_var)
print(myVar)
print(MYVAR)
print(myvar2)

output of this

Abul
Abul
Abul
Abul
Abul
Abul

Examples of the illegal and Prophitted variable names

2myvar = "Abdul"
my-var = "Abdul"
my var = "Abdul"

It will produce an error.

Assign Multiple values to the multiple variables

x, y, z = "Mango", "Apple", "Grapes"
print(x)
print(y)
print(z)
It will produce the output of
Mango
Apple
Grapes

One value to Multiple Variable

x = y = z = "Milk"
print(x)
print(y)
print(z)
The Output is
Milk
Milk
Milk

Unpack the variables

Python allows you to assign variables to the values of the list.

fruits = ["Mango", "Grape", "Apple"]
x, y, z = fruits
print(x)
print(y)
print(z)
It will prints 
Mango
Grape
Apple

In the above example, you have to be careful that the number of variables should be equal to the values. let me give you an example.

fruits = ["Mango", "Grape", "Apple"]
x, y, z, v = fruits
print(x)
print(y)
print(z)

It will prints 
Mango
Grape
Apple

This will produce the error because in the list you have 3 values and you are assigning 4 variables

Output Variable

Normally python print function is used as an output variable

x = 5
print(x)

You can use operator in the print function to display the result

x = 5
y = 10
print(x+y)
The output will be 15

Global Variables

A global variable is one which created outside of the function and can be accessed in the function

Create the variable outside the function and then use that variable inside the function

x = "Fun"

def func():
  print("Python is " + x)

func()
The output of the function is
"Python is Fun"

Exercise

Use subtractoperatorr in the print function

change the value of x to an integer in the global variable