Variables
- Variables are containers for
storing data values.
- Variables is a location in memory
used to store some data (value).
- In Python, variables are Dynamic
(We don't even have to declare the type of the variable).
Rules in Naming a Variable
- Rule 1: A variable name must start with
a letter or the underscore character.
- Rule 2: A variable name cannot start
with a number.
- Rule 3: A variable name can only contain
alpha-numeric characters and underscores (A-Z, 0-9, and _).
- Rule 4: A variable accepts only
underscore _ symbol. (No other symbol is
accepted.)
- Rule 5: Variable names are Case
Sensitive (age, Age and AGE are three different variables).
- Rule 6: It can't accept
reserve/keywords.
Example 1
a
= 9
print(a)
Output:
9
Example 2
A
= 2.0
print(A)
Output:
2.0
Example 3
z
= "Lokesh"
print(z)
Output:
Lokesh
Example 4
a1
= 40
print(a1)
Output:
40
Example 5
a_1
= 60
print(a_1)
Output:
60
Many Values to Multiple Variables
- Python allows you to assign
values to multiple variables in one line.
a, b, c = 10, 20, 30
print(a)
print(b)
print(c)
Output:
10
20
30
Note: Make sure the number of variables matches the number of values, or else
you will get an error.
One Value to Multiple Variables
- You can assign the same value to
multiple variables in one line.
a = b = c = "AI"
print(a)
print(b)
print(c)
Output:
AI
AI
AI
Storage Location
- In Python, objects are created
based on value.
- id() — used to get address.
Example
a = 10
id(a)
Output:
2855789685328
b = 10
id(b)
Output:
2855789685328
Delete Variable
To delete a single variable
a = 10
del a
After deleting the variable:
print(a)
Output:
NameError: name 'a' is not defined
To delete multiple variables at a time
a = 10
b = 20
c = 30
del a, b
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