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13 Python

Basic Data types

Q.1 What are the basic data types in Python

Ans: The basic data types in Python are:

  • Integer: represents whole numbers.
  • Float: represents decimal numbers.
  • String: represents a sequence of characters.
  • Boolean: represents either True or False.
  • List: represents an ordered collection of elements.

Q.2 How do you convert a string to an integer in Python?

You can use the int() function to convert a string to an integer. For example:

num_str = "10"
num_int = int(num_str)

Q.3 How do you check the data type of a variable in Python?

You can use the "type ()" function to check the data type of a variable. For example:

num = 10
print(type(num)) # Output: ‹class 'int'›

Q.4 What is the difference between a list and a tuple in

A list is mutable, which means you can modify its elements, while a tuple is immutable, meaning its elements cannot be changed after creation.

Q.5 How do you create an empty dictionary in Python?

You can create an empty dictionary using either the curly braces {} or the dict() function. For

example:

empty_dict = {}
empty_dict = dict()

Topic 2 OOPS concept in Python:

Q.1 What is OOPS and how is it implemented in Python?

Object-Oriented Programming (OOPS) is a programming paradigm that uses objects to represent real-world entities.

In Python, OOPS is implemented through classes and objects. Classes are blueprints for creating objects, and objects are instances of a class.

Q.2 What are the four principles of OOPS?

Ans: The four principles of OOPS are:

  • • Encapsulation: bundling of data and methods that operate on that data within a single unit (class).
  • • Inheritance: ability of a class to inherit properties and methods from its parent class.
  • • Polymorphism: ability of an object to take on different forms or behaviors based on the context.
  • • Abstraction: representing essential features and hiding unnecessary details to simplify the complexity.

以下是 Python 面向对象编程（Object-Oriented Programming）特性的中文翻译：

  • 封装（Encapsulation）：将数据及操作数据的方法捆绑在单一单元（类）中。
  • 继承（Inheritance）：子类继承父类属性和方法的能力。
  • 多态（Polymorphism）：对象根据上下文呈现不同形式或行为的能力。
  • 抽象（Abstraction）：通过展现核心特征并隐藏非必要细节来简化复杂性。

封装： 强调数据与方法的整合，通过访问控制（如私有变量 _var）实现信息隐藏

继承: 子类复用父类逻辑（class Child(Parent)），支持多层继承和方法重写

多态

  • 方法重写（子类覆写父类方法）
  • 鸭子类型（不同对象实现相同方法名）
class Dog:
    def speak(self): print("汪汪")

class Cat:
    def speak(self): print("喵喵")

def animal_sound(obj):  # 多态调用
    obj.speak()

抽象

通过抽象基类（ABC）或接口设计，聚焦核心功能：

from abc import ABC, abstractmethod
class Shape(ABC):
    @abstractmethod
    def area(self):  # 强制子类实现核心逻辑
        pass

Q.5 What is the difference between a class method and an instance method in Python?

Ans: A class method is a method bound to the class and not the instance of the class.

It is defined using the @classmethod decorator and can access only class-level variables.

On the other hand, an instance method is bound to the instance of the class and can access both instance and class-level

Topic 3 String handling functions

Q.1 How do you concatenate two strings in Python?

You can concatenate two strings using the + operator. For example:

str1 = "Hello"
str2 = "World"
result = stri + str2 # Output: "HelloWorld":

Q.2 How do you find the length of a string in Python?

You can use the len() function to find the length of a string. For example:

str1 = "Hello World"
length = len(str1) # Output:

Q.3 How do you convert a string to uppercase in Python?

Ans: You can use the upper) method to convert a string to uppercase. For example:

str1 = "hello"
uppercase_str = str1. upper) # Output: "HELLO"

Q.4 How do you split a string into a list of substrings in Python?

You can use the split（) method to split a string into a list of substrings based on a delimiter. For example:

str1 = "Hello,World"
substrings = str1.split(",")

# Output: ["Hello",World"]

Q.5 How do you check if a string contains a specific substring in Python?

You can use the in keyword to check if a substring is present in a string. For example:

str1 = "Hello World"
is_present = "World" in str1 # Output: True

Topic 4 Control statements, functions in Python:

if condition:
# Code block executed if the condition is

True else:
# Code block executed if the condition is
False

Q.3 How do you define a function in Python?

A function in Python is defined using the def keyword. For example:

def greet():
    print("Hello, world!")

Q.4 How do you pass arguments to a function in Python?

def greet (name):
    print("Hello," + name + "!")

Q.5 How do you return a value from a function in Python?

def add (a, b):
 return a + b

Topic 5 Special data types in Python:

Q.1 What is a set in Python?

A set in Python is an unordered collection of unique elements.

my_set =  {1,2,3} #Output: {1,2,3}

Q.2 What is a dictionary in Python?

my_dict = {"name": "John", "age": 25}

Q.3 How do you access values in a dictionary in Python?

You can access values in a dictionary by using the corresponding key. For example:

my_dict = {"name": "John", "age": 25}
print(my_dict["name"]) # Output: "John"

Q.4 What is a tuple in Python?

A tuple in Python is an ordered and immutable collection of elements. It is defined using parentheses () or the tuple() constructor. For example:

my_tuple = (1, 2, 3) # Output: (1, 2, 3)

Q.5 How do you swap the values of two variables in Python?

a = 5
b = 10
a, b = b, a
print(a, b) # Output: 10, 5

3 Lambda functions， list comprehension:

Q.1 What is a lambda function in Python?

A lambda function is an anonymous function defined using the lambda keyword. It is typically used for short, one-line functions. For example:

square = lambda x: x**2
print (square (3)) # Output: 9

Q.2 What is list comprehension in Python?

List comprehension is a concise way to create lists in Python based on existing lists or other iterables. It combines the creation of a new list with a loop and optional conditional statements. For example:

numbers = [1, 2, 3, 5]
squared_numbers = [x**2 for x in numbers]
print(squared_numbers)

# Output: [1, 4, 9, 16, 25]

Q.3 How do you filter elements in a list using list

You can filter elements in a list using list comprehension by adding a conditional statement.

For example, to filter even numbers:

numbers = [1, 2, 3,4, 5]
even_numbers = Ix for x in numbers if x % 2 == 0]
print (even_numbers) # Output: [2, 4]

Q.4 Can you have multiple if conditions in list comprehension?

Yes, you can have multiple if conditions in list comprehension by chaining them using the and or or operators. 

numbers = [1, 2, 3, 4, 5]
filtered_numbers = [x for x in numbers if x % 2==0 and x > 2]
print(filtered_numbers) 

# Output: [4]

Q.5 How do you create a dictionary using list comprehension in Python?

Ans: You can create a dictionary using list comprehension by specifying key-value pairs within curly braces {}.

For example:

keys = ['a', 'b', 'c']
values = [1, 2, 3]
my_dict = {k: v for k, v in zip(keys, values)}
print(my_dict) 

# Output: {'a': 1, 'b': 2, 'c': 3}