文件及IO操作 1. 读取文件# 读取文件 import os # 绝对路径 # absolute_path = os.getcwd() # file_name = absolute_path + '/test.txt' # f = open(file_name, mode='r', encoding='utf-8') # 相对路径 f = open('test.txt', mode='r', encoding='utf-8') # content = f.read() # 读取全部 # content = f.readline() # 读取一行 content = f.readlines() # 按行读取 print(content) # 关闭 f.close() 2. 写文件# 写文件 f = open('test.txt', mode='w', encoding='utf-8') f.write('大家好\n') write_content = ['孙笑川\n', '刘波\n'] f.writelines(write_content) f.close() f = open('test.txt', mode='r', encoding='utf-8') read_content = f.read() print(read_content) f.close() 3. 追加写# 追加写 f = open('test.txt', mode='a', encoding='utf-8') f.write('你好\n') content = ['带带大师兄\n', '药水哥\n'] f.writelines(content) f.close() 4. with# with open() as f 操作文件 with open('test.txt', mode='r', encoding='utf-8') as f: print(f.read()) print('使用with语法糖读取文件内容完成')

模块 此处以 random、正则、socket 为例1. random# random import random # 随机小数 print(random.random()) # 1 - 10 之间的随机数 print(random.randint(1, 10)) 2. 正则# 正则 import re # \d 数字 result = re.match(r'\d+', '123abc') print(result) # 123 # \w 数字、字母、下划线 result = re.match(r'\w+', '1a2b3c!') print(result) # 1a2b3c # \s 空白字符串；\S 非空字符串 result = re.match(r'^\s+$', '1 2 3') print(result) # None result = re.match(r'^\S+$', '1 abc') print(result) # None # . 任意字符 result = re.match(r'.+$', 'abc 1q2') print(result) # abc 1q2 # [] 区间 result = re.match(r'^a[1a]', 'a123456') print(result) # a1 # | 或 result = re.match(r'^a|1|c$', 'a12345c') print(result) # a 3. socket3.1 server# socket import socket sk = socket.socket() sk.bind(('127.0.0.1', 8088)) sk.listen(5) conn, addr = sk.accept() print(conn) print(addr) while True: accept_data = conn.recv(1024) print('收到客户端发送的消息：', accept_data.decode('utf-8')) send_data = input('请输入要回复的消息：') conn.send(send_data.encode('utf-8'))3.2 client# socket import socket sk = socket.socket() sk.connect(('127.0.0.1', 8088)) while True: sand_data = input('请输入要发送的消息：') sk.send(sand_data.encode('utf-8')) accept_data = sk.recv(1024) print(accept_data.decode('utf-8'))

函数 1. 函数# 函数 def say_hello(name): print('大家好，我叫', name) say_hello('孙笑川') # 可变参数 def test(*args): print(args) test(1, 2, 3, 4) def test_1(**kwargs): for key, value in kwargs.items(): print(key, value) test_1(**{'name': '孙笑川', 'age': 33, 'address': '成都'}) 2. 变量的作用域# 变量的作用域 # 不可变数据类型 index = 1 # 可变数据类型 list = [1, 2, 3] def test(): global index # 全局变量 index = 20 index1 = 30 list[1] = 300 test() # print('函数执行完后打印index1的值', index1) # 报错 Unresolved reference 'index1' print('函数执行完后打印index的值', index) # 20 print('函数执行完后打印list的值', list) # [1, 300, 3] 3. 匿名函数# 匿名函数 test = lambda x, y: x + y print(test(1, 2)) arr = [1, 2, 3, 4] # 映射 result = map(lambda x: x ** 2, arr) print(list(result)) # 归约 from functools import reduce print(reduce(lambda x, y: x * y, arr)) # 过滤 print(list(filter(lambda x: x % 2 != 0, arr)))

异常处理 # 异常处理 try: n = int(input('请输入被除数：')) i = 10 / n print(i) except ZeroDivisionError as e: print('除数不能为0') except: print('请输入正确的数字！') else: print('未被except捕获') finally: print('执行完毕') print('----------------------') # 抛出异常 try: n = input('请输入一个任意数字：') if not n.isdigit(): raise Exception('输入的内容有误，请检查！') else: print('您输入的数字是：%d' % n) except Exception as e: print(e)

组合数据类型 1. 列表# 列表 list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] print(list) # 索引 print(list[1]) # 切片 print(list[::-1]) # 内置函数 print(min(list)) print(max(list)) print(len(list)) print('-------------------------') # 遍历 for i in list: print(i) for i, index in enumerate(list): print(i, index) for i in range(len(list)): print(i, list[i]) # 常用方法 # 添加元素 list.append('a') list.extend('extend') print(list) print('-------------------------') # 插入元素 list.insert(1, 'b') print(list) print('-------------------------') # 根据索引删除元素 list.pop(1) print(list) print('-------------------------') # 删除指定元素 list.remove(1) print(list) print('-------------------------') # 清空列表 list.clear() print(list) 2. 元组# 元组 tuple1 = (1, 2, 3, 4, 5, 6) print(type(tuple1)) print(tuple1) temp_tuple = (1,) # 元组中只有一个元素时，加一个逗号 print(type(temp_tuple)) print('-------------------------') # 类型转换 # str ---> tuple print(tuple('abc')) # list ---> tuple print(tuple([1, 2, 3])) print('-------------------------') # 索引 print(tuple1[1]) # 切片 print(tuple1[::-1]) # 常用方法 print(min(tuple1)) print(max(tuple1)) print(len(tuple1)) print('-------------------------') # 遍历 for i in tuple1: print(i) for index, item in enumerate(tuple1): print(index, item) for i in range(len(tuple1)): print(tuple1[i]) 3. 字符串# 字符串 str = 'sunxiaochuan,liubo' print(min(str)) print(max(str)) print(len(str)) print('-------------------------') # 遍历 for i in str: print(i) for index, item in enumerate(str): print(index, item) for i in range(len(str)): print(str[i]) print('-------------------------') # 常用方法 print(str.islower()) print(str.isupper()) print(str.count('c')) print(str.split(',')) print(str.find('l')) 4. 字典# 字典 d = {} print(type(d)) # <class 'dict'> # 新增值（键值对） d['name'] = 'sunxiaochuan' d['age'] = 33 print(d) # 获取键值对 print(d['name']) # 修改 d['age'] = 30 print(d) print('-------------------------') # 遍历 for i in d: print(i, d[i]) for k, v in d.items(): print(f'{k} = {v}') for k in d.keys(): print(k) for value in d.values(): print(value) print('-------------------------') # 常用方法 # d.pop('name') # print(d) new_dictionary = d.copy() print(new_dictionary) name = d.get('name') print(name) # d.popitem() # print(d) d.update({'age': 50}) print(d) 5. 集合# 集合 s = set() s = {1, 2, 3, 4, 5} # s1 = set([1, 2, 3, 4, 5]) # list ---> set # s2 = set((1, 2, 3, 4, 5)) # tuple ---> set # s3 = set('12345') # str ---> list # s4 = set({'key1': 'value1', 'key2': 1}) # dict ---> list # 常用方法 print(1 in s) print(len(s)) print(min(s)) print(max(s)) # del s # 删除集合 s.add('a') print(s) s.remove(1) print(s) s.update({'a', 'b', 'c'}) print(s) print('-------------------------') # 遍历 for i in s: print(i) print('-------------------------') s1 = {1, 2, 3, 'a', 88} s2 = {'c', 'b', 3, 1, 'f'} print(s1 & s2) # 交集 print(s1 | s2) # 并集 print('-------------------------') # 去重 s3 = set([1, 1, 2, 3, 4, 5, 6, 6, 7]) print(s3)

循环 1. while# while index = 0 while index < 100: print(index) index += 1 2. for# for for i in range(100): print(i) # 求n的阶乘 result = 0 index = 1 while index <= 5: current_result = 1 m = 1 while m <= index: current_result = current_result * m m += 1 result += current_result index += 1 print("5的阶乘为：%d" % result) 3. break# break for i in range(10): print(i) if i == 3: print("结束循环") break 4. continue# continue for i in range(10): if i == 5: continue print(i)

条件判断 1. 单分支# 单分支 flag = 1 if flag == 1: print("标志位为1") if True: print("符合判断条件")2. 双分支# 双分支 flag = 1 if flag == 1: print("标志位为1") else: print("标志位不为1") if True: print("符合判断条件") else: print("不符合判断条件") 3. 多分支# 多分支 flag = 1 if flag == 1: print("标志位为1") elif flag == 2: print("标志位为2") elif flag == 3: print("标志位为3") else: print("未匹配到对应的标志位") 4. match# match flag = 1 match flag: case 1: print("标志位为1") case 2: print("标志位为2") case 3: print("标志位为3") case _: print("未匹配到对应的标志位")

运算符与表达式 1. 算术运算符# 算术运算符 a = 1 b = 2 # 加 print(a + b) # 减 print(a - b) # 乘 print(a * b) # 除 print(a / b) # 整除（取整） print(a // b) # 求模 print(a % b) # 幂运算 print(a ** 2) 2. 赋值运算符# 赋值运算符 a = 1 # 自增 a += 1 print(a) # 自减 a -= 1 print(a) 3. 比较运算符# 比较运算符 a = 1 b = 2 # 不等于 != print(a != b) # 等于 == print(a == b) # 字符串比较（比较的是每个字符的ascii码值） print("abc" < "efg") print("abc" == False) 4. 逻辑运算符# 逻辑运算符 # 与 and print(1 and 2) print(False and True) print("abc" and "edg") # 短路运算，按字符顺序比较，当第一个字符 e > a 时，返回edg # 或 or print(1 or 2) print(0 or 1) print(False or True) # 非 not print(not 1) print(not False) print(not "") # 三者之间的优先级关系 not > and > or print(True or False and not False) 5. 位运算符# 位运算符 # 按位与 & ''' 101 111 --- 101 ''' print(5 & 7) # 按位或 | ''' 101 111 --- 111 ''' print(5 | 7) # 按位异或 ''' 101 111 --- 010 ''' print(5 ^ 7) # 按位取反 ~ ''' 101 --- 010 ''' print(~5) # 左移 右移 ''' 101 --- 10100 ''' print(5 << 2) 6. 成员运算符# 成员运算符 str = "这是一个字符串" print("a" in str) a = 1 b = 2 print(a is b) print(a is not b)