Python

Variables and Data Types in Python

Python 150 views Nov 05, 2025 1 min read

Variables and Data Types in Python

Variables in Python are used to store data. Python automatically detects the data type when a variable is assigned.

1. Variable Rules

  • Must start with a letter or underscore.

  • Can contain letters, digits, and underscores.

  • Cannot be a Python keyword.

  • Python is case-sensitive (age and Age are different).

name = "Alice"
_age = 25
number1 = 100

2. Basic Data Types

Data TypeDescriptionExample
intInteger numbersx = 10
floatDecimal numbersy = 3.14
strString (text)name = "Python"
boolBoolean valuesis_valid = True
complexComplex numbersz = 2 + 3j

3. Type Conversion (Casting)

x = 10        # int
y = float(x)  # convert int to float
z = str(x)    # convert int to string

print(type(x))  # 
print(type(y))  # 
print(type(z))  #

4. Multiple Assignment

  • Assign values to multiple variables in one line:

a, b, c = 5, 10, 15
x = y = z = 20

5. Checking Data Type

  • Use type() function to check the data type:

value = 3.14
print(type(value))  #

6. Constants

  • By convention, constants are uppercase:

PI = 3.14159
GRAVITY = 9.8

7. Key Points

  • Variables store data values for later use.

  • Python infers the data type automatically.

  • Basic data types include int, float, str, bool, and complex.

  • Multiple variables can be assigned in one line.

  • Use type() to check the data type.

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