Python基础之基本数据类型一《数字与字符串》

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一、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"
  

二、基本数据类型

         数字 int

               1. int    将字符串转换为数字

                          a = "123" 

                          print(type(a),a)   此处a的数据类型为字符串

                          b = int(a)

                          print(type(b),b)   此处b的数据类型为数字

               2. bit_lenght    当前数字的二进制至少用N位表示                          r = age.bit_lenght()

         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

                     *  填充内容,一个字符,可有可无

                     test = "alex"

 

                     v = test.center(20,"中")   #字符串在中间

                        v = test.ljust(20,"*")     #字符串在左面填充右面

                        v = test.rjust(20,"*")    #字符串在右面

                        v = test.zfill(20)      #用0填充空白

 

                        print(v)

 

                    4. 在字符串中寻找,寻找子序列的出现次数

                           test = "aLexalexr"

 

                           v = test.count(‘ex‘)

                           v = test.count(‘ex‘,5,6)   #5,6为在这个区间内找子序列的出现次数

 

                           print(v)

 

                    5. 以什么什么开始,以什么什么结尾

                           test = "alex"

                          

                           v = test.startswith(‘ex‘)   #开始

                           v = test.endswith(‘ex‘)     #结尾

 

                           print(v)

 

                    6. 制表符,断句

                           test = "username\temail\tpassword\nlaiying\[email protected]\t123\nlaiying\[email protected]\t123\nlaiying\[email protected]\t123"
                           v = test.expandtabs(20)      #设置每个\t隔开的间距包括其中的字符总共为20

                           print(v)

                       

                    7. 从开始往后找,找到第一个之后,获取其位置

                           test = "alexalex"  

                           v = test.find(‘ex‘)   #只获取第一次出现的位置,未找到为 -1

                           print(v)

                          

                    8. 查找索引位置, 找不到报错

                           test = "alexalex"

                           v = test.index(‘e‘)    #如有重复只获取第一个

                           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 {0}, age {1}"

                           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})

 

                            print(v1,v2)

 

                    11. 判断字符串中是否只包含 字母和数字

                             test = "123"

                             v = test.isalnum()

                             print(v)

 

                    12. 判断是否是字母,汉子

                             test = "as2df"

                             v = test.isalpha()

                             print(v)

 

                    13. 当前输入是否是数字

                             test = "二"  

                             v1 = test.isdecimal()     #只能判断普通数字                 

                             v2 = test.isdigit()    # 类似1,②的也能判断

                             v3 = test.isnumeric()   #能判断各种类型数字

                             print(v1,v2,v3)

 

                    14. 判断不存在不可显示的字符

                             test = "oiuas\tdfkj"

                             v = test.isprintable()   # \t,\n 就为不可显示字符

                             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(每个单词首字母大写)

                         test = "Return True if all cased characters in S are uppercase and there is"

                            

                         v = test.istitle()

                         v = test.title()   #转换为标题

 

                         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"

                             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"

 

                           v = test.islower()   #是不是小写

                           v = test.lower()      #转换为小写

                           v = test.isupper()    #是不是大写

                           v = test.upper()    #转换为大写

 

                            print(v)

 

                     19. 移除指定字符串

                              test = "  xa   "

                              v = test.strip(‘xa‘)  #移除指定字符

                              v = test.lstrip()  #移除左面字符

                              v = test.rstrip()   #移除右面字符

                              print(v)

 

                     20.  对应关系替换

                              v = "asidufkasd;fiuadkf;adfkjalsdjf"

                              m = str.maketrans("aeiou", "12345")         #后面的替换前面的            

                              new_v = v.translate(m)

                              print(new_v)

 

                     21. 分割为三部分

                              test = "testasdsddfg"

                              v = test.partition(‘s‘)    #以第一个出现的分割

                              v = test.rpartition(‘s‘)    #以右面第一个分割

                              print(v)

 

                     22. 用指定个数的字符分割

                              test = "testasdsddfg"

                              v = test.split(‘s‘,2)    #从左边开始

                              v = test.rsplit(‘s‘,2)     #从右边开始

                              print(v)

 

                     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.  判断以xxx开头,以xxx结尾

                              test = "backend 1.1.1.1"

                              v = test.startswith(‘a‘)   #以a开头

                              test.endswith(‘a)    # 以a结尾

                              print(v)

 

                      25. 大小写转换

                               test = "aLex"

                               v = test.swapcase()

                               print(v)

 

                      26.  将指定字符串替换为指定字符串

                               test = "alexalexalex"

                               v = test.replace("ex",‘bbb‘)

                               v = test.replace("ex",‘bbb‘,2)   #数字为指定替换的个数

                               print(v)

###################### 7个基本魔法 ######################

                        1. join     将指定字符串插入到原字符串得每个字符中间,组成新的字符串

                        2. split    用指定个数的字符分割

                        3. find     从开始往后找,找到第一个之后,获取其位置

                        4. strip    移除指定字符串

                        5. upper  全部变为大写

                        6. lower   全部变为小写

                        7. replace  将指定字符串替换为指定字符串

###################### 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)

       


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



 





































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