必备Python代码段

以下是一些常用的Python代码段，用于不同的编程任务：

1. 读取文件内容：

def read_file(file_path):
    try:
        with open(file_path, 'r') as file:
            content = file.read()
            return content
    except FileNotFoundError:
        return "File not found."
    except Exception as e:
        return f"An error occurred: {e}"

2. 列表推导：

numbers = [1, 2, 3, 4, 5]
squared = [x ** 2 for x in numbers]

3. 字典操作：

student = {'name': 'John', 'age': 20, 'grade': 'A'}
student['school'] = 'XYZ School'

4. 条件判断：

age = 18
if age >= 18:
    print("You are an adult.")
else:
    print("You are a minor.")

5. 循环遍历：

fruits = ['apple', 'banana', 'orange']
for fruit in fruits:
    print(fruit)

6. 函数定义：

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

7. 异常处理：

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Division by zero is not allowed.")
except Exception as e:
    print(f"An error occurred: {e}")

8. 类定义：

class Dog:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def bark(self):
        print("Woof!")

9. 模块导入：

import math
sqrt_value = math.sqrt(25)

10. 文件写入：

data = "Hello, world!"
with open('output.txt', 'w') as file:
    file.write(data)

这些代码段涵盖了Python编程中常见的操作，可帮助你进行文件操作、数据处理、条件判断、循环遍历、异常处理等任务。根据你的需求，可以将这些代码段作为基础，进行进一步的定制和扩展。