Python Tutorials
Python Introduction
Python Get Started
Python Syntax
Python Comments
Python Variables
Python Data Types
Python Casting
Python Strings
Python Booleans
Python Operators
Python Lists
Python Tuples
Python Sets
Python Dictionaries
Python If...Else
Python While Loops
Python For Loops
Python Functions
Python Lambda
Python Arrays
Python Classes/Objects
Python Inheritance
Python Iterators
Python Scope
Python Modules
Python Dates
Python Math
Python JSON
Python RegEx
Python PIP
Python Try..Except
Python User Input
Python String Formatting
Python File Handling
Python File Handling
Python Read Files
Python Create/Write Files
Python Delete Files
Python Modules
Python Numpy
Python Pandas
Python SciPy
Previous
Python Variables
Variables
Variables are data storage containers.
Creating Variables
Python has no dynamic declaration command.
Variables are created when you first give value to it.
Example
x = 5
y = "John"
print(x)
print(y)
Variables do not need to be declared in any particular format, and can change even genre after setup.
Example
x = 4 # x is of type int
x = "Sally" # x is now of type str
print(x)
Casting
If you want to specify a variant data type, this can be done by streaming.
Example
x =
str(3) # x will be '3'
y = int(3) # y
will be 3
z = float(3) # z will be 3.0
Get the Type
You can get the type of data variable with the type() function.
Example
x = 5
y = "John"
print(type(x))
print(type(y))
Single or Double Quotes?
Cable variables can be announced using one or two quotes:
Example
x = "John"
# is the same as
x =
'John'
Case-Sensitive
Flexible words are very sensitive.
Example
a = 4
A =
"Sally"
#A will not overwrite a
Python - Variable Names
Variable Names
Variables can have a shorter word (such as x and y) or a more descriptive word (age, carname, total_ volume). Python flexibility rules:
- The variable word should start with a letter or underscore character
- A different name cannot start with a number
- A different name may contain only alpha-numeric characters and underscore (A-z, 0-9, and _)
- The most sensitive variables are (age, age and AGE are three different variables)
Example
Legal variable names:
myvar = "John"
my_var = "John"
_my_var = "John"
myVar = "John"
MYVAR = "John"
myvar2 = "John"
Example
Illegal variable names:
2myvar = "John"
my-var = "John"
my var = "John"
Remember that flexible words are very sensitive
Multi Words Variable Names
Flexible words with more than one word can be difficult to read.
There are several strategies you can use to make it more readable:
Camel Case
Each word, except the first one, begins with a capital letter:
myVariableName = "John"
Pascal Case
Each word begins with a capital letter:
Snake Case
Each word is separated by an underscore character:
my_variable_name = "John"
Python Variables - Assign Multiple Values
Many Values to Multiple Variables
Python lets you assign multiple values to a single line:
Example
x, y, z = "Orange", "Banana", "Cherry"
print(x)
print(y)
print(z)
Note: Make sure the value of the variables is the same as the value of the values, otherwise you will get an error.
One Value to Multiple Variables
You can also assign the same number of multiple variables in a single line:
Example
x = y = z = "Orange"
print(x)
print(y)
print(z)
Unpack a Collection
If you have a set of values in the list, tuple etc. Python lets you extract values into variables. This is called disassembly.
Example
Unpack a list:
fruits = ["apple", "banana", "cherry"]
x, y, z = fruits
print(x)
print(y)
print(z)
Python - Output Variables
Output Variables
Python print statement is often used for flexible output.
Combining both text and flexibility, Python uses the character +:
Example
x = "awesome"
print("Python is " + x)
You can also use the character + to add variables to other variables:
Example
x = "Python is "
y = "awesome"
z = x + y
print(z)
In numbers, the character + acts as a mathematical operator:
Example
x = 5
y = 10
print(x + y)
If you try to combine a unit of letters with a number, Python will give you an error:
Example
x = 5
y = "John"
print(x + y)
Python - Global Variables
Global Variables
The variables created outside of work (as in all the examples above) are known as global variables.
Global variables can be used by everyone, both internally and externally.
Example
Create a variable outside of a function, and use it inside the function
x = "awesome"
def myfunc():
print("Python is " + x)
myfunc()
If you create variables with the same name within a function, these variations will be local, and can only be used within the function. Global variation of the same name will remain as it was, global and real value.
Example
Create a variable inside a function, with the same name as the global variable
x = "awesome"
def myfunc():
x = "fantastic"
print("Python is " + x)
myfunc()
print("Python is " + x)
The global Keyword
Usually, when you create a variable within a function, that variation is local, and can only be used within that function
To create a global dynamic within a function, you can use a global keyword.
Example
If you use the global keyword, the variable belongs to the global scope:
def myfunc():
global x
x = "fantastic"
myfunc()
print("Python is " + x)
Also, use a global keyword if you want to change the global variable within a function.
Example
To change the value of a global variable inside a function, refer to the variable by using the global keyword:
x = "awesome"
def myfunc():
global x
x = "fantastic"
myfunc()
print("Python is " + x)