復制來的基礎知識
阿新 • • 發佈：2018-04-01
類型 clas 不可 adk tuple return 設置 左右 字符串
今日內容： 1. 條件語句 1. 基本 2. 嵌套 3. if elif else ... 2. while循環 while 條件： .... print(‘...‘) 補充： a. while else b. continue break continue, 終止當前循環，開始下一次循環 break, 終止所有循環 用戶登陸（三次機會重試） count = 0 while count < 3: user = input(‘>>>‘) pwd = input(‘>>>‘) if user == ‘alex‘ and pwd == ‘123‘: print(‘歡迎登陸‘) print(‘..........‘) break else: print(‘用戶名或者密碼錯誤‘) count = count + 1 python開發IDE： pycharm、eclipse # 專業版 # 不要漢化 1、運算符 結果是值 算數運算 a = 10 * 10 賦值運算 a = a + 1 a += 1 結果是布爾值 比較運算 a = 1 > 5 邏輯運算 a = 1 > 6 or 1 == 1 成員運算 a = "蚊" in "鄭建文" 2、基本數據類型 數字 int ，所有的功能，都放在int裏 a1 = 123 a1 = 456 - int 將字符串轉換為數字 a = "123" print(type(a), a) b = int(a) print(type(b), b) num = "0011" v = int(num, base=16) print(v) - bit_lenght # 當前數字的二進制，至少用n位表示 r = age.bit_length() 字符串 str ########################################### # 1 首字母大寫 # test = "aLex" # v= test.capitalize() # print(v) # 2 所有變小寫，casefold更牛逼，很多未知的對相應變小寫 # v1 = test.casefold() # print(v1) # v2 = test.lower() # print(v2) # 3 設置寬度，並將內容居中 # 20 代指總長度 # * 空白未知填充，一個字符，可有可無 # 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 去字符串中尋找，尋找子序列的出現次數 # test = "aLexalexr" # v = test.count(‘ex‘) # print(v) # test = "aLexalexr" # v = test.count(‘ex‘,5,6) # print(v) # 欠 # encode # decode # 5 # 以什麽什麽結尾 # 以什麽什麽開始 # test = "alex" # v = test.endswith(‘ex‘) # v = test.startswith(‘ex‘) # print(v) # 6 expandtabs,斷句20， # test = "username\temail\tpassword\nlaiying\[email protected]\t123\nlaiying\[email protected]\t123\nlaiying\[email protected]\t123" # v = test.expandtabs(20) # print(v) # 7 從開始往後找，找到第一個之後，獲取其未知 # > 或 >= # test = "alexalex" # 未找到 -1 # v = test.find(‘ex‘) # print(v) # 8 index找不到，報錯 忽略 # test = "alexalex" # v = test.index(‘8‘) # print(v) # 9 格式化，將一個字符串中的占位符替換為指定的值 # 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，傳入的值 {"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 字母和數字 # test = "123" # v = test.isalnum() # print(v) # str # 12 是否是字母，漢子 # test = "as2df" # v = test.isalpha() # print(v) # 13 當前輸入是否是數字 # test = "二" # 1，② # v1 = test.isdecimal() # v2 = test.isdigit() # v3 = test.isnumeric() # print(v1,v2,v3) # 14 是否存在不可顯示的字符 # \t 制表符 # \n 換行 # test = "oiuas\tdfkj" # v = test.isprintable() # print(v) # 15 判斷是否全部是空格 # test = "" # v = test.isspace() # print(v) # 16 判斷是否是標題 # 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 ***** 將字符串中的每一個元素按照指定分隔符進行拼接 # test = "你是風兒我是沙" # print(test) # # t = ‘ ‘ # v = "_".join(test) # print(v) # 18 判斷是否全部是大小寫 和 轉換為大小寫 # 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 對應關系替換 # test = "aeiou" # test1 = "12345" # v = "asidufkasd;fiuadkf;adfkjalsdjf" # m = str.maketrans("aeiou", "12345") # new_v = v.translate(m) # print(new_v) # 21 分割為三部分 # test = "testasdsddfg" # v = test.partition(‘s‘) # print(v) # v = test.rpartition(‘s‘) # print(v) # 22 分割為指定個數 # v = test.split(‘s‘,2) # print(v) # test.rsplit() # 23 分割，只能根據，true，false：是否保留換行 # test = "asdfadfasdf\nasdfasdf\nadfasdf" # v = test.splitlines(False) # print(v) # 24 以xxx開頭，以xx結尾 # test = "backend 1.1.1.1" # v = test.startswith(‘a‘) # print(v) # test.endswith(‘a) # 25 大小寫轉換 # test = "aLex" # v = test.swapcase() # print(v) # 26 字母，數字，下劃線 ： 標識符 def class # a = "def" # v = a.isidentifier() # print(v) # 27 將指定字符串替換為指定字符串 # test = "alexalexalex" # v = test.replace("ex",‘bbb‘) # print(v) # v = test.replace("ex",‘bbb‘,2) # print(v) ###################### 7個基本魔法 ###################### # join # ‘_‘.join("asdfasdf") # split # find # strip # upper # lower # replace ###################### 4個灰魔法 ###################### # test = "鄭建文妹子有種沖我來" # 一、for循環 # for 變量名 in 字符串: # 變量名 # break # continue # index = 0 # while index < len(test): # v = test[index] # print(v) # # index += 1 # print(‘=======‘) # for zjw in test: # print(zjw) # test = "鄭建文妹子有種沖我來" # for item in test: # print(item) # break # for item in test: # continue # print(item) # 二、索引，下標，獲取字符串中的某一個字符 # v = test[3] # print(v) # 三、切片 # v = test[0:-1] # 0=< <1 # print(v) # 四、獲取長度 # Python3： len獲取當前字符串中由幾個字符組成 # v = len(test) # print(v) # 註意： # len("asdf") # for循環 # 索引 # 切片 # 五、獲取連續或不連續的數字， # Python2中直接創建在內容中 # python3中只有for循環時，才一個一個創建 # r1 = range(10) # r2 = range(1,10) # r3 = range(1,10,2) # 幫助創建連續的數字,通過設置步長來指定不連續 # v = range(0, 100, 5) # # for item in v: # print(item) ##### 練習題：根據用戶輸入的值，輸出每一個字符以及當前字符所在的索引位置 ##### # test = input(">>>") # for item in test: # print(item) # 將文字 對應的索引打印出來： # 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個深灰魔法 ###################### # 字符串一旦創建，不可修改 # 一旦修改或者拼接，都會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 ... 布爾值 bool ...
復制來的基礎知識