Python Data Types | Mutable and Immutable Data Types | Complete Notes | CBSE Class 11 Informatics Practices (2026–27)
Class 11 · Informatics Practices
Python Data Types | Mutable and Immutable Data Types
Every value stored in Python belongs to a particular data type. A data type tells Python what kind of data is being stored and what operations can be performed on it. Choosing the correct data type makes programs efficient, readable, and less prone to errors.
What is a Data Type?
A data type specifies the type of value stored in a variable and determines the operations that can be performed on that value.
Example
```python age = 16 name = "Rahul" marks = 92.5 passed = True ``` Here, - `16` is an integer. - `"Rahul"` is a string. - `92.5` is a floating-point number. - `True` is a Boolean value.Built-in Data Types in Python
| Category | Data Type | Example |
|---|---|---|
| Numeric | int | 25 |
| Numeric | float | 85.75 |
| Numeric | complex | 3+4j |
| Boolean | bool | True |
| Text | str | "Python" |
| Sequence | list | [10,20,30] |
| Mapping | dict | {"A":90} |
Note: Although list and dictionary are discussed later in the syllabus, they are also built-in Python data types.
Integer (int)
The int data type stores whole numbers without a decimal point.
Examples
```python roll_no = 25 temperature = -8 population = 1400000000 ```Floating-Point (float)
The float data type stores numbers containing a decimal point.
Examples
```python percentage = 87.5 height = 165.2 price = 99.99 ```Complex Numbers (complex)
Python supports complex numbers, which contain a real part and an imaginary part represented using j.
Examples
```python z1 = 4+5j z2 = 2-3j ```Boolean (bool)
A Boolean value represents one of two possible values: True or False.
Examples
```python result = True eligible = False ``` Boolean values are commonly used in decision-making statements.String (str)
A string is a sequence of characters enclosed in single quotes, double quotes, or triple quotes.
Examples
```python name = "Rahul" city = 'Jaipur' message = """Welcome to Python""" ```Checking the Data Type
The type() function returns the data type of a value or variable.
Program
```python a = 25 b = 15.8 c = "Python" d = True print(type(a)) print(type(b)) print(type(c)) print(type(d)) ``` Output ```textMutable and Immutable Data Types
Python data types are classified as mutable or immutable depending on whether their values can be changed after creation.
Mutable Data Types
A mutable object can be modified after it is created.
Examples
- List
- Dictionary
- Set
Program
```python marks = [70,80,90] marks[1] = 85 print(marks) ``` Output ```text [70, 85, 90] ``` The list changes without creating a new object.Immutable Data Types
An immutable object cannot be modified after it is created. Any modification creates a new object.
Examples
- int
- float
- bool
- str
- tuple
Program
```python name = "Python" name = name + " Programming" print(name) ``` Output ```text Python Programming ``` The original string is not modified. Instead, a new string object is created.Mutable vs Immutable Data Types
| Feature | Mutable | Immutable |
|---|---|---|
| Can be modified | Yes | No |
| Memory | Same object can be updated | New object is created |
| Examples | List, Dictionary | int, float, bool, str, tuple |
Real-Life Examples
| Situation | Data Type |
|---|---|
| Student Roll Number | int |
| Percentage | float |
| Student Name | str |
| Pass/Fail Status | bool |
| Marks of Subjects | list |
| Student Details | dict |
Common Errors
| Mistake | Correct Concept |
|---|---|
| Using quotes around numbers. | "25" is a string, not an integer. |
| Writing true or false in lowercase. | Python uses True and False. |
| Assuming strings are mutable. | Strings are immutable. |
| Thinking lists cannot be modified. | Lists are mutable. |
| Confusing int and float. | Integers have no decimal point; floats do. |
Quick Revision
| Concept | Remember |
|---|---|
| int | Whole numbers |
| float | Decimal numbers |
| complex | Numbers with imaginary part |
| bool | True or False |
| str | Sequence of characters |
| Mutable | Can be modified |
| Immutable | Cannot be modified |
CBSE Exam Tips
- Know the difference between int, float, complex, bool, and str.
- Remember which data types are mutable and which are immutable.
- Practice using the type() function.
- Do not confuse strings containing digits with numeric values.
- Remember that Boolean values are written as True and False.
Summary
Python provides several built-in data types for storing different kinds of information. Numeric data types include integers, floating-point numbers, and complex numbers, while Boolean values represent logical conditions and strings store text. Python also classifies data types as mutable or immutable based on whether their values can be changed after creation. A clear understanding of data types is essential for writing efficient and error-free Python programs.