FUTURE OF TANZANIA
Python I
Python Home
Python Install
Python Intro
Python Syntax
Python Comments
Python Variables
Python User Input
Python Data Types
Python Numbers
Python Casting
Python Strings
Python Booleans
Python Operators
Python II
Python Lists
Python Tuples
Python Sets
Python Dictionaries
Python If Else
Python While Loops
Python For Loops
Python Functions
Python Arrays
Python Scope
Python Math
Python String Formatting
Python File Handling
Python Read Files
Python Write/Create Files
Python Delete Files
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Python Variables
Variables
Creating Variables
Casting
Get the Type
Single or Double Quotes
Case-Sensitive
Variable Names
Assign Values to Variables
Output Variables
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Variables
Variables are containers for storing data values.
Creating Variables
Python has no command for declaring a variable.
A variable is created the moment you first assign a value to it.
x = 5
y = "John"
print(x)
print(y)
Variables do not need to be declared with any particular type, and can even
change type after they have been set.
x = 4 # x is of type int
x = "Sally" # x is now of type str
print(x)
Casting
If you want to specify the data type of a variable, this can be done with casting.
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 data type of a variable with the type() function.
x = 5
y = "John"
print(type(x))
print(type(y))
Single or Double Quotes?
String variables can be declared either by using single or double quotes:
x = "John"
# is the same as
x = 'John'
Case-Sensitive
Variable names are case-sensitive.
This will create two variables:
a = 4
A = "Sally"
#A will not overwrite a
Variable Names
A variable can have a short name (like x and y) or a more descriptive name (age,
carname, 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)
Legal variable names:
myvar = "John"
my_var = "John"
_my_var = "John"
myVar = "John"
MYVAR = "John"
myvar2 = "John"
Illegal variable names:
2myvar = "John"
my-var = "John"
my var = "John"
Note:
Remember that variable names are case-sensitive
Multi Words Variable Names
Variable names with more than one word can be difficult to read.
There are several techniques you can use to make them more readable:
Camel Case
Each word, except the first, starts with a capital letter:
myVariableName = "John"
Pascal Case
Each word starts with a capital letter:
MyVariableName = "John"
Snake Case
Each word starts with a capital letter:
my_variable_name = "John"
Many Values to Multiple Variables
Python allows you to assign values to multiple variables in one line:
x, y, z = "Orange", "Banana", "Cherry"
print(x)
print(y)
print(z)
Note
: Make sure the number of variables matches the number of values, or else
you will get an error.
One Value to Multiple Variables
And you can assign the same value to multiple variables in one line:
x = y = z = "Orange"
print(x)
print(y)
print(z)
Unpack a Collection
If you have a collection of values in a list, tuple etc. Python allows you to extract
the values into variables. This is called
unpacking
.
Update a list:
fruits = ["apple", "banana", "cherry"]
x, y, z = fruits
print(x)
print(y)
print(z)
Output Variables
The Python print() function is often used to output variables.
x = "Python is awesome"
print(x)
In the print() function, you output multiple variables, separated by a comma:
x = "Python"
y = "is"
z = "awesome"
print(x, y, z)
You can also use the + operator to output multiple variables:
x = "Python "
y = "is "
z = "awesome"
print(x + y + z)
Note:
Notice the space character after "Python " and "is ", without them the result
would be "Pythonisawesome".
For numbers, the + character works as a mathematical operator:
x = 5
y = 10
print(x + y)
In the print() function, when you try to combine a string and a number with
the + operator, Python will give you an error:
x = 5
y = "John"
print(x + y)
The best way to output multiple variables in the print() function is to separate
them with commas, which even support different data types:
x = 5
y = "John"
print(x, y)
All curriculum credit goes to
w3schools.com
Python Comments
Python User Input
Python I
Python Home
Python Install
Python Intro
Python Syntax
Python Comments
Python Variables
Python User Input
Python Data Types
Python Numbers
Python Casting
Python Strings
Python Booleans
Python Operators
Python II
Python Lists
Python Tuples
Python Sets
Python Dictionaries
Python If Else
Python While Loops
Python For Loops
Python Functions
Python Arrays
Python Scope
Python Math
Python String Formatting
Python File Handling
Python Read Files
Python Write/Create Files
Python Delete Files
Picture
youtube
notion