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Python Variables

Variables in Python are used to store data values. Python creates a variable at the moment you assign a value to it, which makes variable handling simple and flexible.

Creating Variables

In Python, variables are created without declaring a data type. You just assign a value using the = operator.
Python automatically determines the type of the variable.

Code Example 1: Creating Variables

python
x = 10
name = "Python"
price = 99.99

Code Example 2: Reassigning Variables

python
x = 5
x = 20
print(x)

Code Example 3: Multiple Variables

python
a, b, c = 1, 2, 3
print(a, b, c)
Key Point

Python variables are dynamically typed.

Casting

Casting means specifying a data type for a variable. Python allows you to convert values from one type to another.
Common casting functions:
  • int()
  • float()
  • str()

Code Example 1: Integer Casting

python
x = int(10.5)
print(x)

Code Example 2: Float Casting

python
y = float(5)
print(y)

Code Example 3: String Casting

python
z = str(100)
print(z)
Important

Casting helps control how data is stored and processed.

Get the Type

Python provides the type() function to check the data type of a variable.
This is useful for debugging and learning.

Code Example 1: Check Integer Type

python
x = 10
print(type(x))

Code Example 2: Check String Type

python
name = "Python"
print(type(name))

Code Example 3: Check Float Type

python
price = 19.99
print(type(price))

Single or Double Quotes?

In Python, strings can be created using single quotes (' ') or double quotes (" "). Both are treated the same by Python.
Use double quotes when the string contains single quotes.

Code Example 1: Single Quotes

python
text = 'Hello Python'
print(text)

Code Example 2: Double Quotes

python
text = "Hello Python"
print(text)

Code Example 3: Mixed Quotes

python
text = "Python is a 'high-level' language"
print(text)
Best Practice

Be consistent with quote style throughout your code.

Case-Sensitive

Python is a case-sensitive language. This means variable names with different letter cases are treated as different variables.

Code Example 1: Case Sensitivity

python
age = 25
Age = 30
print(age)
print(Age)

Code Example 2: Invalid Assumption

python
value = 10
# print(Value)  # This will cause an error

Code Example 3: Recommended Naming Style

python
user_name = "Admin"
print(user_name)
Caution

Always use consistent naming to avoid confusion and errors.

Summary

  • Variables store data values
  • Created automatically on assignment
  • Casting converts data types
  • type() checks variable type
  • Strings support single and double quotes
  • Python is case-sensitive

Exercise

  • Create variables of different types
  • Convert one type into another using casting
  • Use type() to verify the result