Learn Python Variables

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Variables

Variables are used to store data that can be referenced and manipulated in a program. In Python, variables are created by assigning a value to a name using the assignment operator =. Python is dynamically typed, meaning you don't need to declare the type of a variable before using it. The type is inferred from the value assigned.

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Creating Variables

To create a variable, simply assign a value to a name:.

Example-
name = "Alice"
age = 25
height = 5.7
is_student = True

In this example:

• name is a string variable.
• age is an integer variable.
• height is a float variable
• is_student is a boolean variable.

2. Variable Naming Rules

When naming variables in Python, you need to follow these rules:

• Variable names must start with a letter (a-z, A-Z) or an underscore (_).
• The rest of the name can contain letters, digits (0-9), and underscores.
• Variable names are case-sensitive (e.g., age, Age, and AGE are different variables).
• Avoid using Python reserved keywords (e.g., class, for, if, else, etc.).

Examples:

Example-
user_name = "Alice"
_user_age = 25
userHeight = 5.7
isStudent = True

3. Assigning Multiple Variables

You can assign multiple variables in one line:

Example-
a, b, c = 1, 2, 3

You can also assign the same value to multiple variables in one line:

Example-
x = y = z = 0

4. Variable Types

Python automatically determines the type of the variable based on the value assigned. You can check the type of a variable using the type() function.

Examples:

Example-
name = "Alice"
age = 25
height = 5.7
is_student = True
print(type(name))
print(type(age))
print(type(height))
print(type(is_student))

5. Changing Variable Types

You can change the type of a variable by assigning a value of a different type:

Example-
number = 10
number = "Ten"
print(number)

6. Constants

By convention, constants are usually defined using uppercase letters. Although Python does not have built-in constant types, it's a common practice to define constants at the beginning of the script.

Example-
PI = 3.14159
MAX_USERS = 100

7. Deleting Variables

You can delete a variable using the del keyword:

Example-
x = 10
print(x) # Output: 10
del x
# print(x) # This will raise a NameError because x is deleted