Python Basics: Variables, Data Types, Control Flow, Functions, and More

1️⃣ Variable Declaration and Assignment

Python variables are created by simple assignment without prior declaration.

# Python中变量无需提前声明，直接赋值即可
age = 25  # 声明并初始化整型变量
name = "Alice"  # 声明并初始化字符串变量
is_student = True  # 声明并初始化布尔型变量

2️⃣ Data Types

Python supports lists, tuples, and dictionaries among other built‑in types.

# Python支持多种数据类型，如列表、元组、字典
fruits = ['apple', 'banana', 'cherry']  # 列表
coordinates = (40.7128, -74.0060)  # 元组
person_info = {'name': 'Tom', 'age': 30, 'city': 'New York'}  # 字典

3️⃣ Conditional Statements and Loops

Use if…elif…else for branching and for / while for iteration.

# if...elif...else...
score = 85
if score >= 90:
    print("优秀")
elif score >= 80:
    print("良好")
else:
    print("需加油")
# for loop over a list
for fruit in fruits:
    print(fruit)
# while loop
i = 0
while i < len(fruits):
    print(fruits[i])
    i += 1

4️⃣ Function Definition and Call

# 定义一个函数
def greet(name):
    return f"Hello, {name}!"
# 调用函数
print(greet("World"))  # 输出: Hello, World!

5️⃣ List Comprehension

# 列表推导式快速生成新列表
squares = [x**2 for x in range(1, 6)]
print(squares)  # 输出: [1, 4, 9, 16, 25]

6️⃣ Exception Handling

try:
    age = int(input("请输入您的年龄："))
    print(age)
except ValueError:
    print("输入错误，请确保输入的是数字！")

7️⃣ Classes and Objects

# 定义一个简单的Person类
class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
# 创建Person对象并访问属性
p = Person("Bob", 30)
print(p.name)  # 输出: Bob
print(p.age)   # 输出: 30

8️⃣ Iterators and Generator Expressions

# 生成器表达式
gen_numbers = (x for x in range(1, 6))
for num in gen_numbers:
    print(num)
# 使用next()获取生成器的下一个值
gen = (x for x in range(10))
print(next(gen))  # 输出: 0

9️⃣ Decorators

# 定义一个装饰器，用于计算函数执行时间
import time

def timer_decorator(func):
    def wrapper(*args, **kwargs):
        start_time = time.time()
        result = func(*args, **kwargs)
        end_time = time.time()
        print(f"{func.__name__}执行耗时：{end_time - start_time}秒")
        return result
    return wrapper

@timer_decorator
def long_running_task():
    time.sleep(2)

long_running_task()

🔟 Module Import and Package Management

# 导入标准库math模块
import math
print(math.sqrt(16))  # 输出: 4.0
# 导入模块中特定函数或变量
from math import sqrt
print(sqrt(16))  # 输出: 4.0

By practicing these snippets, readers can solidify their understanding of Python's core concepts and build a strong foundation for more advanced programming tasks.