今日内容： 1. 条件语句 1. 基本 2. 嵌套 3. if elif else ... 2. while循环 while 条件： .... print(‘...‘) 补充： a. while else b. continue break continue, 终止当前循环，开始下一次循环 break, 终止所有循环 用户登陆（三次机会重试） count = 0 while count < 3: user = input(‘>>>‘) pwd = input(‘>>>‘) if user == ‘alex‘ and pwd == ‘123‘: print(‘欢迎登陆‘) print(‘..........‘) break else: print(‘用户名或者密码错误‘) count = count + 1 python开发IDE： pycharm、eclipse # 专业版 # 不要汉化 1、运算符 结果是值 算数运算 a = 10 * 10 赋值运算 a = a + 1 a += 1 结果是布尔值 比较运算 a = 1 > 5 逻辑运算 a = 1 > 6 or 1 == 1 成员运算 a = "蚊" in "郑建文" 2、基本数据类型 数字 int ，所有的功能，都放在int里 a1 = 123 a1 = 456 - int 将字符串转换为数字 a = "123" print(type(a), a) b = int(a) print(type(b), b) num = "0011" v = int(num, base=16) print(v) - bit_lenght # 当前数字的二进制，至少用n位表示 r = age.bit_length() 字符串 str ########################################### # 1 首字母大写 # test = "aLex" # v = test.capitalize() # print(v) # 2 所有变小写，casefold更牛逼，很多未知的对相应变小写 # v1 = test.casefold() # print(v1) # v2 = test.lower() # print(v2) # 3 设置宽度，并将内容居中 # 20 代指总长度 # * 空白未知填充，一个字符，可有可无 # v = test.center(20,"中") # print(v) # test = "alex" # v = test.ljust(20,"*") # print(v) # test = "alex" # v = test.rjust(20,"*") # print(v) # test = "alex" # v = test.zfill(20) # print(v) # 4 去字符串中寻找，寻找子序列的出现次数 # test = "aLexalexr" # v = test.count(‘ex‘) # print(v) # test = "aLexalexr" # v = test.count(‘ex‘,5,6) # print(v) # 欠 # encode # decode # 5 # 以什么什么结尾 # 以什么什么开始 # test = "alex" # v = test.endswith(‘ex‘) # v = test.startswith(‘ex‘) # print(v) # 6 expandtabs,断句20， # test = "username\temail\tpassword\nlaiying\[email protected]\t123\nlaiying\[email protected]\t123\nlaiying\[email protected]\t123" # v = test.expandtabs(20) # print(v) # 7 从开始往后找，找到第一个之后，获取其未知 # > 或 >= # test = "alexalex" # 未找到 -1 # v = test.find(‘ex‘) # print(v) # 8 index找不到，报错 忽略 # test = "alexalex" # v = test.index(‘8‘) # print(v) # 9 格式化，将一个字符串中的占位符替换为指定的值 # test = ‘i am {name}, age {a}‘ # print(test) # v = test.format(name=‘alex‘,a=19) # print(v) # test = ‘i am {0}, age {1}‘ # print(test) # v = test.format(‘alex‘,19) # print(v) # 10 格式化，传入的值 {"name": ‘alex‘, "a": 19} # test = ‘i am {name}, age {a}‘ # v1 = test.format(name=‘df‘,a=10) # v2 = test.format_map({"name": ‘alex‘, "a": 19}) # 11 字符串中是否只包含 字母和数字 # test = "123" # v = test.isalnum() # print(v) # str # 12 是否是字母，汉子 # test = "as2df" # v = test.isalpha() # print(v) # 13 当前输入是否是数字 # test = "二" # 1，② # v1 = test.isdecimal() # v2 = test.isdigit() # v3 = test.isnumeric() # print(v1,v2,v3) # 14 是否存在不可显示的字符 # \t 制表符 # \n 换行 # test = "oiuas\tdfkj" # v = test.isprintable() # print(v) # 15 判断是否全部是空格 # test = "" # v = test.isspace() # print(v) # 16 判断是否是标题 # test = "Return True if all cased characters in S are uppercase and there is" # v1 = test.istitle() # print(v1) # v2 = test.title() # print(v2) # v3 = v2.istitle() # print(v3) # 17 ***** 将字符串中的每一个元素按照指定分隔符进行拼接 # test = "你是风儿我是沙" # print(test) # # t = ‘ ‘ # v = "_".join(test) # print(v) # 18 判断是否全部是大小写 和 转换为大小写 # test = "Alex" # v1 = test.islower() # v2 = test.lower() # print(v1, v2) # v1 = test.isupper() # v2 = test.upper() # print(v1,v2) # 19 # 移除指定字符串 # 有限最多匹配 # test = "xa" # # v = test.lstrip(‘xa‘) # v = test.rstrip(‘9lexxexa‘) # # v = test.strip(‘xa‘) # print(v) # test.lstrip() # test.rstrip() # test.strip() # 去除左右空白 # v = test.lstrip() # v = test.rstrip() # v = test.strip() # print(v) # print(test) # 去除\t \n # v = test.lstrip() # v = test.rstrip() # v = test.strip() # print(v) # 20 对应关系替换 # test = "aeiou" # test1 = "12345" # v = "asidufkasd;fiuadkf;adfkjalsdjf" # m = str.maketrans("aeiou", "12345") # new_v = v.translate(m) # print(new_v) # 21 分割为三部分 # test = "testasdsddfg" # v = test.partition(‘s‘) # print(v) # v = test.rpartition(‘s‘) # print(v) # 22 分割为指定个数 # v = test.split(‘s‘,2) # print(v) # test.rsplit() # 23 分割，只能根据，true，false：是否保留换行 # test = "asdfadfasdf\nasdfasdf\nadfasdf" # v = test.splitlines(False) # print(v) # 24 以xxx开头，以xx结尾 # test = "backend 1.1.1.1" # v = test.startswith(‘a‘) # print(v) # test.endswith(‘a) # 25 大小写转换 # test = "aLex" # v = test.swapcase() # print(v) # 26 字母，数字，下划线 ： 标识符 def class # a = "def" # v = a.isidentifier() # print(v) # 27 将指定字符串替换为指定字符串 # test = "alexalexalex" # v = test.replace("ex",‘bbb‘) # print(v) # v = test.replace("ex",‘bbb‘,2) # print(v) ###################### 7个基本魔法 ###################### # join # ‘_‘.join("asdfasdf") # split # find # strip # upper # lower # replace ###################### 4个灰魔法 ###################### # test = "郑建文妹子有种冲我来" # 一、for循环 # for 变量名 in 字符串: # 变量名 # break # continue # index = 0 # while index < len(test): # v = test[index] # print(v) # # index += 1 # print(‘=======‘) # for zjw in test: # print(zjw) # test = "郑建文妹子有种冲我来" # for item in test: # print(item) # break # for item in test: # continue # print(item) # 二、索引，下标，获取字符串中的某一个字符 # v = test[3] # print(v) # 三、切片 # v = test[0:-1] # 0=< <1 # print(v) # 四、获取长度 # Python3： len获取当前字符串中由几个字符组成 # v = len(test) # print(v) # 注意： # len("asdf") # for循环 # 索引 # 切片 # 五、获取连续或不连续的数字， # Python2中直接创建在内容中 # python3中只有for循环时，才一个一个创建 # r1 = range(10) # r2 = range(1,10) # r3 = range(1,10,2) # 帮助创建连续的数字,通过设置步长来指定不连续 # v = range(0, 100, 5) # # for item in v: # print(item) ##### 练习题：根据用户输入的值，输出每一个字符以及当前字符所在的索引位置 ##### # test = input(">>>") # for item in test: # print(item) # 将文字 对应的索引打印出来： # test = input(">>>") # print(test) # test = qwe test[0] test[1] # l = len(test) # l = 3 # print(l) # # r = range(0,l) # 0,3 # for item in r: # print(item, test[item]) # 0 q,1 w,2 e # test = input(">>>") # for item in range(0, len(test)): # print(item, test[item]) ###################### 1个深灰魔法 ###################### # 字符串一旦创建，不可修改 # 一旦修改或者拼接，都会造成重新生成字符串 # name = "zhengjianwen" # age = "18" # # info = name + age # print(info) 列表 list ... 元祖 tuple ... 字典 dict ... 布尔值 bool ...