Python Variables


Variables are data storage containers.

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Creating Variables

Python doesn't have a commanding for declaring variables.

When you first assign a value to variable, it is created.

Example 1 :-

x = 5
y = "John"
print(x)
print(y)

Output :-

5
John

Variables with no particular type must be declared, and after they are specified they can even change type.

Example 2 :-

x = 4
x = "Sally"
print(x)

Output :-

Sally

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Casting

Casting is a technique for specifying the data type of a variable.

Example :-

x = str(3)
y = int(3)
z = float(3)

print(x)
print(y)
print(z)

Output :-

3
3
3.0

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Get the Type

The type() function can be used to determine the data type of a variable.

Example :-

x = 5
y = "John"
print(type(x))
print(type(y))

Output :-

<class 'int'>
<class 'str'>

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Single or Double Quotes?

Example :- Single or double quotes are used to declare string variables :

x = "John"
print(x)

#double quotes are the same as single quotes:

x = 'John'
print(x)

Output :-

John
John


Case-Sensitive

The case-sensitive is important in variable names.

Example :- This will result in the following two variables :

a = 4
A = "Sally"

print(a)
print(A)

Output :-

4
Sally

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Variable Names and Naming Rules

A variable will have a short name (such as x and y) or a longer name (such as age, carname, or total volume). Python variables have rules :

  • A variable name must begin with a letter or an underscore.
  • A number cannot be the first character in a variable name.
  • Only alpha-numeric characters and underscores (A-z, 0-9, and_ ) are used in variable names.
  • Case matters when naming variables (age, Age and AGE three distinct variables).

Example :- A few variable names are :

# Valid Variable Names

myvar = "John"
my_var = "John"
_my_var = "John"
myVar = "John"
MYVAR = "John"
myvar2 = "John"

# Invalid Variable Names

2myvar = "John"
my-var = "John"
my var = "John"

Note:- Always keep in mind that variable names are case sensitive.

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Multi Words Variable Names

It can be hard to read names that contain more than one word.

If you want to make them more readable, you can use a variety of methods.

Camel Case

A capital letter appears at the beginning of every word except first one :

myVariableName = "John"

Pascal Case

A capital letter is used to begin every word :

MyVariableName = "John"

Snake Case

The underscore character is used to divide each word in a variable name :

my_variable_name = "John"
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Python Variables - Assign Multiple Values

You can declare multiple variable and define their value at once in many ways.

Many Values to Multiple Variables

Example :- In Python, you can assign values to multiple variables in a single line by using a function :

x, y, z = "Orange", "Banana", "Cherry"

print(x)
print(y)
print(z)

Output :-

Orange
Banana
Cherry

Note :- You'll get an error if the number of variables doesn't equal the number of values.

One Value to Multiple Variables

Example :- It's also possible to assign the same value to many variables in a single line :

x = y = z = "Orange"

print(x)
print(y)
print(z)

Output :-

Orange
Orange
Orange

Unpack a Collection

Python allows you to extract values from a list, tuple, etc. Unpacking is the process of removing the contents of a package.

Example :-

fruits = ["apple", "banana", "cherry"]
x, y, z = fruits

print(x)
print(y)
print(z)

Output :-

apple
banana
cherry

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Output Variables

print statements are commonly used to output variables in Python.

Example 1 :- Python + character is used to combine text and a variable :

x = "awesome"
print("Python is " + x)

Output :-

Python is awesome

Example 2 :- Add a variable to another by using the + symbol :

x = "Python is "
y = "awesome"
z = x + y
print(z)

Output :-

Python is awesome

Example 3 :- The + character is a mathematical operator for numbers :

x = 5
y = 10
print(x + y)

Output :-

15

Example 4 :- Python will throw an error if you try to combine a string and a number :

x = 5
y = "John"
print(x + y)

Output :-

TypeError: unsupported operand type(s) for +: 'int' and 'str'

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Global Variables

Global variables are variables that are created outside of a function (as in the examples above).

Everybody, both within and outside of functions, can use global variables.

Example 1 :- Create a variable outside of a function and utilise it within the function :

x = "awesome"

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

myfunc()

Output :-

Python is awesome

Creating a variable with the same name inside a function makes it local, meaning it may only be used within the function. There will be no change to the original global variable with the same name.

Example 2 :- Create a variable with the same name as the global variable within a function :

x = "awesome"

def myfunc():
  x = "fantastic"
  print("Python is " + x)

myfunc()

print("Python is " + x)

Output :-

Python is fantastic
Python is awesome

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The global Keyword

A variable created within a function is normally local and can only be utilised within that function.

The global keyword can be used to define a global variable within a function.

Example 1 :- The variable is in the global scope if you use the global keyword :

def myfunc():
  global x
  x = "fantastic"

myfunc()

print("Python is " + x)

Output :-

Python is fantastic


If you want to alter a global variable within a function, use the global keyword.

Example 2 :- Use the global keyword to modify the value of a global variable within a function :

x = "awesome"

def myfunc():
  global x
  x = "fantastic"

myfunc()

print("Python is " + x)

Output :-

Python is fantastic

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