一篇文章学透所有Python知识（建议收藏）

在本文中，我们将深入探讨Python编程的八大核心知识点，并提供多个实例代码，帮助读者更好地理解和运用这些知识点。

第一部分：基础语法

1. 变量的定义与使用

name = "John"
age = 25

2. 数据类型操作

num1 = 10
num2 = 5
result = num1 + num2
print(result)

3. 条件语句

score = 85
if score >= 90:
    print("优秀")
elif score >= 80:
    print("良好")
else:
    print("及格")

4. 循环结构

for i in range(1, 6):
    print(i)

第二部分：函数和模块

1. 函数的定义与调用

def add(a, b):
    return a + b
result = add(3, 4)
print(result)

2. 参数传递

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

3. 创建和使用模块

# math_utils.py
def square(num):
    return num ** 2

# main.py
import math_utils
result = math_utils.square(5)
print(result)

第三部分：面向对象编程

1. 类的定义和使用

class Person:
    def __init__(self, name):
        self.name = name


    def greet(self):
        print("Hello, my name is " + self.name)


person = Person("John")
person.greet()

2. 对象的创建和操作

class Circle:
    def __init__(self, radius):
        self.radius = radius
    def area(self):
        return 3.14 * self.radius ** 2
circle = Circle(5)
print(circle.area())

3. 继承和多态

class Animal:
    def sound(self):
        pass


class Dog(Animal):
    def sound(self):
        print("Woof!")


class Cat(Animal):
    def sound(self):
        print("Meow!")


dog = Dog()
cat = Cat()
dog.sound()
cat.sound()

第四部分：文件操作

1. 读取文件

with open("data.txt", "r") as file:
    data = file.read()
    print(data)

2. 写入文件

with open("output.txt", "w") as file:
    file.write("Hello, World!")

第五部分：异常处理

1. 捕获和处理异常

try:
    num = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero.")

2. 优雅地处理错误

def divide(a, b):
    try:
        result = a / b
    except ZeroDivisionError:
        result = None
    finally:
        return result
print(divide(10, 2))
print(divide(10, 0))

第六部分：数据结构和算法

1. 列表操作

numbers = [1, 2, 3, 4, 5]
print(len(numbers))
print(numbers[2])

2. 字典操作

person = {"name": "John", "age": 25}
print(person["name"])
print(person.get("age"))

3. 排序算法

numbers = [5, 2, 8, 1, 9]
numbers.sort()
print(numbers)

第七部分：网络编程

1. Socket编程

import socket


server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.bind(("localhost", 8080))
server_socket.listen(1)


client_socket, address = server_socket.accept()
print("Connection from: " + str(address))
client_socket.close()
server_socket.close()

2. HTTP协议应用

import requests
response = requests.get("https://www.example.com")
print(response.text)

第八部分：数据库编程

1. 访问数据库

import sqlite3
connection = sqlite3.connect("database.db")
cursor = connection.cursor()
cursor.execute("SELECT * FROM students")
data = cursor.fetchall()
for row in data:
    print(row)
connection.close()