Python Variables

Creating Variables

Unlike other programming languages, Python has no command for declaring a variable.

A variable is created the moment you first assign a value to it.

Example

x = 5
y = "John"
print(x)
print(y)

Show Python »
C:\Users\My Name>python demo_variables1.py
5                                         
John                                      
                                          
                                          

Variables do not need to be declared with any particular type and can even change type after they have been set.

Example

x = 4 # x is of type intx = "Sally" # x is now of type strprint(x)

Show Python »
C:\Users\My Name>python demo_variables2.py
Sally                                     
                                          
                                          

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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)

Remember that variables are case-sensitive

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Output Variables

The Python print statement is often used to output variables.

To combine both text and a variable, Python uses the + character:

Example

x = "awesome"
print("Python is " + x)

Show Python »
C:\Users\My Name>python demo_variables3.py
Python is awesome                         
                                          
                                          

You can also use the + character to add a variable to another variable:

Example

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

Show Python »
C:\Users\My Name>python demo_variables4.py
Python is awesome                         
                                          
                                          

For numbers, the + character works as a mathematical operator:

Example

x = 5
y = 10
print(x + y)

Show Python »
C:\Users\My Name>python demo_variables5.py
15                                        
                                          
                                          

If you try to combine a string and a number, Python will give you an error:

Example

x = 5
y = "John"
print(x + y)

Show Python »
C:\Users\My Name>python demo_variables_test.py               
TypeError: unsupported operand type(s) for +: 'int' and 'str'