100个python的基本语法知识【上】

roc-ever 2024-07-27 10:05:07 阅读 85

0. 变量和赋值:

x = 5

name = “John”

1. 数据类型:

整数(int)

浮点数(float)

字符串(str)

布尔值(bool)

2. 注释:

<code># 这是单行注释

"""

这是

多行注释

"""

3. 算术运算:

a + b # 加法

a - b # 减法

a * b # 乘法

a / b # 除法

a % b # 取余

a ** b # 幂运算

4. 比较运算:

a == b # 等于

a != b # 不等于

a > b # 大于

a < b # 小于

a >= b # 大于等于

a <= b # 小于等于

5. 逻辑运算:

a and b

a or b

not a

6. 条件语句:

if condition:

# do something

elif another_condition:

# do something else

else:

# do something different

7. 循环:

for i in range(5):

print(i)

while condition:

# do something

8. 列表:

my_list = [1, 2, 3]

my_list.append(4)

my_list[0] # 访问元素

9. 元组:

my_tuple = (1, 2, 3)

10. 字典:

my_dict = { "name": "John", "age": 30}

my_dict["name"] # 访问键值

11. 集合:

my_set = { 1, 2, 3}

my_set.add(4)

12. 字符串操作:

s = "hello"

s.upper()

s.lower()

s.split(" ")

s.replace("h", "j")

13. 字符串格式化:

name = "John"

age = 30

f"Hello, { name}. You are { age}."

14. 列表解析:

squares = [x**2 for x in range(10)]

15. 函数定义:

def my_function(param1, param2):

return param1 + param2

16. 默认参数:

def my_function(param1, param2=5):

return param1 + param2

17. 关键字参数:

def my_function(param1, param2):

return param1 + param2

my_function(param2=10, param1=5)

18. 可变参数:

def my_function(*args):

for arg in args:

print(arg)

my_function(1, 2, 3)

19. 关键字可变参数:

def my_function(**kwargs):

for key, value in kwargs.items():

print(f"{ key}: { value}")

my_function(name="John", age=30)code>

20. lambda表达式:

f = lambda x: x**2

f(5)

21. map函数:

list(map(lambda x: x**2, range(10)))

22. filter函数:

list(filter(lambda x: x % 2 == 0, range(10)))

23. reduce函数:

from functools import reduce

reduce(lambda x, y: x + y, range(10))

24. 异常处理:

try:

# do something

except Exception as e:

print(e)

finally:

# cleanup

25. 文件读取:

with open("file.txt", "r") as file:

content = file.read()

26. 文件写入:

with open("file.txt", "w") as file:

file.write("Hello, World!")

27. 类定义:

class MyClass:

def __init__(self, param1):

self.param1 = param1

def my_method(self):

return self.param1

28. 类继承:

class MyBaseClass:

def __init__(self, param1):

self.param1 = param1

class MyDerivedClass(MyBaseClass):

def __init__(self, param1, param2):

super().__init__(param1)

self.param2 = param2

29. 魔法方法:

class MyClass:

def __init__(self, param1):

self.param1 = param1

def __str__(self):

return f"MyClass with param1={ self.param1}"

30. 属性和装饰器:

class MyClass:

def __init__(self, value):

self._value = value

@property

def value(self):

return self._value

@value.setter

def value(self, new_value):

self._value = new_value

31. 生成器:

def my_generator():

yield 1

yield 2

yield 3

for value in my_generator():

print(value)

32. 列表解析和生成器表达式:

[x**2 for x in range(10)]

(x**2 for x in range(10))

33. 集合解析:

{ x**2 for x in range(10)}

34. 字典解析:

{ x: x**2 for x in range(10)}

35. 上下文管理器:

with open("file.txt", "r") as file:

content = file.read()

36. 装饰器:

def my_decorator(func):

def wrapper(*args, **kwargs):

print("Before function call")

result = func(*args, **kwargs)

print("After function call")

return result

return wrapper

@my_decorator

def my_function():

print("Function call")

my_function()

37. 类型注解:

def my_function(param1: int, param2: str) -> str:

return param2 * param1

38. 枚举:

from enum import Enum

class Color(Enum):

RED = 1

GREEN = 2

BLUE = 3

39. 迭代器:

class MyIterator:

def __init__(self, start, end):

self.current = start

self.end = end

def __iter__(self):

return self

def __next__(self):

if self.current >= self.end:

raise StopIteration

else:

self.current += 1

return self.current - 1

40. JSON解析:

import json

json_str = '{"name": "John", "age": 30}'

data = json.loads(json_str)

41. 日期和时间:

from datetime import datetime

now = datetime.now()

42. 随机数生成:

import random

random_number = random.randint(1, 10)

43. 数学运算:

import math

math.sqrt(16)

44. 模块和包:

# my_module.py

def my_function():

return "Hello"

# main.py

import my_module

my_module.my_function()

45. 命名空间:

global_var = 5

def my_function():

local_var = 10

global global_var

global_var = 20

46. 继承和多态:

class Animal:

def speak(self):

pass

class Dog(Animal):

def speak(self):

return "Woof"

class Cat(Animal):

def speak(self):

return "Meow"

47. 操作系统交互:

import os

os.getcwd()

os.listdir(".")

48. 命令行参数:

import sys

for arg in sys.argv:

print(arg)

49. 正则表达式:

import re

pattern = r"\d+"

re.findall(pattern, "There are 2 apples and 5 bananas.")



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