day14 python02---字符串

day02

数字相关的转换

bin() 2进制
oct() 8进制
hex() 16进制

字符串

定义：它是一个有序的字符的集合，用于存储和表示基本的文本信息，‘’或“”或‘’‘ ’‘’中间包含的内容称之为字符串
特性：
1.只能存放一个值
2.不可变
3.按照从左到右的顺序定义字符集合，下标从0开始顺序访问，有序
补充：
　　1.字符串的单引号和双引号都无法取消特殊字符的含义，如果想让引号内所有字符均取消特殊意义，在引号前面加r，如name＝r'l\thf'
　　2.unicode字符串与r连用必需在r前面，如name＝ur'l\thf' 

 class str(object):
     def capitalize(self):
         首字母变大写

     def center(self, width, fillchar=None):
         原来字符居中，不够用空格补全

     def count(self, sub, start=None, end=None):
         从一个范围内的统计某str出现次数

     def encode(self, encoding='utf-8', errors='strict'):
         以encoding指定编码格式编码，如果出错默认报一个ValueError，除非errors指定的是

     def endswith(self, suffix, start=None, end=None):
         Return True if S ends with the specified suffix, False otherwise.

     def expandtabs(self, tabsize=8):
         将字符串中包含的\t转换成tabsize个空格

     def find(self, sub, start=None, end=None):
         Return the lowest index in S where substring sub is found

     def format(self, *args, **kwargs):
         格式化输出
         三种形式：
         形式一.
         >>> print('{0}{1}{0}'.format('a','b'))
         aba

         形式二：（必须一一对应）
         >>> print('{}{}{}'.format('a','b'))
         Traceback (most recent call last):
           File "<input>", line 1, in <module>
         IndexError: tuple index out of range
         >>> print('{}{}'.format('a','b'))

         形式三：
         >>> print('{name} {age}'.format(age=12,name='lhf'))

     def index(self, sub, start=None, end=None):
         查找第一个出现该字符串的下标

     def isalpha(self):
         至少一个字符，且都是字母才返回True

     def isdigit(self):
         如果都是整数，返回True

     def isidentifier(self):
         字符串为关键字返回True

     def islower(self):
         至少一个字符，且都是小写字母才返回True

     def isnumeric(self):
         Return True if there are only numeric characters in S,

     def isspace(self):
         至少一个字符，且都是空格才返回True

     def istitle(self):
         首字母大写则返回True

     def isupper(self): # real signature unknown; restored from __doc__
         Return True if all cased characters in S are uppercase and there is

     def join(self, iterable): # real signature unknown; restored from __doc__
         #对序列进行操作（分别使用' '与':'作为分隔符）
         >>> seq1 = ['hello','good','boy','doiido']
         >>> print ' '.join(seq1)
         hello good boy doiido
         >>> print ':'.join(seq1)
         hello:good:boy:doiido

         #对字符串进行操作

         >>> seq2 = "hello good boy doiido"
         >>> print ':'.join(seq2)
         h:e:l:l:o: :g:o:o:d: :b:o:y: :d:o:i:i:d:o

         #对元组进行操作

         >>> seq3 = ('hello','good','boy','doiido')
         >>> print ':'.join(seq3)
         hello:good:boy:doiido

         #对字典进行操作

         >>> seq4 = {'hello':1,'good':2,'boy':3,'doiido':4}
         >>> print ':'.join(seq4)
         boy:good:doiido:hello

         #合并目录

         >>> import os
         >>> os.path.join('/hello/','good/boy/','doiido')
         '/hello/good/boy/doiido'

         S.join(iterable) -> str

         Return a string which is the concatenation of the strings in the
         iterable.  The separator between elements is S.
         """
         return ""

     def lower(self):
         """
         S.lower() -> str

         Return a copy of the string S converted to lowercase.
         """
         return ""

     def partition(self, sep):
         以sep为分割，将S分成head,sep,tail三部分

     def replace(self, old, new, count=None):
         S.replace(old, new[, count]) -> str
         Return a copy of S with all occurrences of substring

     def rfind(self, sub, start=None, end=None):
         S.rfind(sub[, start[, end]]) -> int

     def rindex(self, sub, start=None, end=None):
         S.rindex(sub[, start[, end]]) -> int

     def rsplit(self, sep=None, maxsplit=-1): # real signature unknown; restored from __doc__
         """
         S.rsplit(sep=None, maxsplit=-1) -> list of strings

         Return a list of the words in S, using sep as the
         delimiter string, starting at the end of the string and
         working to the front.  If maxsplit is given, at most maxsplit
         splits are done. If sep is not specified, any whitespace string
         is a separator.
         """
         return []

     def rstrip(self, chars=None): # real signature unknown; restored from __doc__
         """
         S.rstrip([chars]) -> str

         Return a copy of the string S with trailing whitespace removed.
         If chars is given and not None, remove characters in chars instead.
         """
         return ""

     def split(self, sep=None, maxsplit=-1): # real signature unknown; restored from __doc__
         以sep为分割，将S切分成列表，与partition的区别在于切分结果不包含sep，
         如果一个字符串中包含多个sep那么maxsplit为最多切分成几部分
         >>> a='a,b c\nd\te'
         >>> a.split()
         ['a,b', 'c', 'd', 'e']

     def splitlines(self, keepends=None): # real signature unknown; restored from __doc__
         """
         Python splitlines() 按照行('\r', '\r\n', \n')分隔，
         返回一个包含各行作为元素的列表，如果参数 keepends 为 False，不包含换行符，如        果为 True，则保留换行符。
         >>> x
         'adsfasdf\nsadf\nasdf\nadf'
         >>> x.splitlines()
         ['adsfasdf', 'sadf', 'asdf', 'adf']
         >>> x.splitlines(True)
         ['adsfasdf\n', 'sadf\n', 'asdf\n', 'adf']

         S.splitlines([keepends]) -> list of strings

         Return a list of the lines in S, breaking at line boundaries.
         Line breaks are not included in the resulting list unless keepends
         is given and true.
         """
         return []

     def startswith(self, prefix, start=None, end=None): # real signature unknown; restored from __doc__
         S.startswith(prefix[, start[, end]]) -> bool

         Return True if S starts with the specified prefix, False otherwise.

     def strip(self, chars=None): # real signature unknown; restored from __doc__
         S.strip([chars]) -> str

         Return a copy of the string S with leading and trailing

     def swapcase(self): # real signature unknown; restored from __doc__
         """
         大小写反转
         S.swapcase() -> str

         Return a copy of S with uppercase characters converted to lowercase
         and vice versa.
         """
         return ""

     def title(self): # real signature unknown; restored from __doc__
         """
         S.title() -> str

         Return a titlecased version of S, i.e. words start with title case
         characters, all remaining cased characters have lower case.
         """
         return ""

     def translate(self, table): # real signature unknown; restored from __doc__
         """
         table=str.maketrans('alex','big SB')

         a='hello abc'
         print(a.translate(table))

         S.translate(table) -> str

         Return a copy of the string S in which each character has been mapped
         through the given translation table. The table must implement
         lookup/indexing via __getitem__, for instance a dictionary or list,
         mapping Unicode ordinals to Unicode ordinals, strings, or None. If
         this operation raises LookupError, the character is left untouched.
         Characters mapped to None are deleted.
         """
         return ""

     def upper(self): # real signature unknown; restored from __doc__
         """
         S.upper() -> str

         Return a copy of S converted to uppercase.
         """
         return ""

     def zfill(self, width): # real signature unknown; restored from __doc__
         """
         原来字符右对齐，不够用0补齐

         S.zfill(width) -> str

         Pad a numeric string S with zeros on the left, to fill a field
         of the specified width. The string S is never truncated.
         """
         return ""

str的方法

homework

 # 1：编写for循环，利用索引遍历出每一个字符
 # msg='hello egon 666'

 msg='hello egon 666'

 for i in range(len(msg)):
     print(msg[i])

作业一

 # 2：编写while循环，利用索引遍历出每一个字符
 # msg='hello egon 666'
 msg='hello egon 666'
 count = 0

 while count < len(msg):
     print(msg[count])
     count += 1

作业二

 # 3：
 # msg='hello alex'中的alex替换成SB

 msg='hello alex'

 print(msg)
 print("修改后：",msg.replace('alex', 'SB'))

作业三

 # 4：
 # msg='/etc/a.txt|365|get'
 # 将该字符的文件名，文件大小，操作方法切割出来

 msg='/etc/a.txt|365|get'
 msg_list = msg.split('|')
 print("""
   打印说明
 1.文件名：{}
 2.大  小：{}
 3.方  法：{}
 """.format(msg_list[0], msg_list[1], msg_list[2]))

作业四

 # 编写while循环，要求用户输入命令，如果命令为空，则继续输入

 flag = True
 while flag:
     if len(input(">>>").strip()) != 0:
         flag = False
     continue

作业五

 # 编写while循环，让用户输入用户名和密码，如果用户为空或者数字，则重新输入

 flag = True

 while flag:
     username = input('username:').strip()
     password = input('password:').strip()
     if len(username) != 0 and not username.isdigit():
         flag = False
     continue

作业六

 # 编写while循环，让用户输入内容，判断输入的内容以alex开头的，则将该字符串加上_SB结尾

 while True:
     s = input(">>>")
     if s == 'q':
         break
     elif s.startswith('alex'):
         s+='_SB'
     print(s)

作业七

 # 8.
 # 1.两层while循环，外层的while循环，让用户输入用户名、密码、工作了几个月、每月的工资（整数），用户名或密码为空，或者工作的月数不为整数，或者
 # 月工资不为整数，则重新输入
 # 2.认证成功，进入下一层while循环，打印命令提示，有查询总工资，查询用户身份（如果用户名为alex则打印super user，如果用户名为yuanhao或者wupeiqi
 # 则打印normal user，其余情况均打印unkown user），退出功能
 # 3.要求用户输入退出，则退出所有循环（使用tag的方式）
 flag = True

 while flag:
     username = input('用户名：').strip()
     password = input('密码：').strip()
     work_time = input('工作时间：').strip()
     salary = input('工资：').strip()
     if len(username) == 0 or len(password) == 0 or not work_time.isdigit() or not salary.isdigit():
         continue
     else:
         while flag:
             choose = input("1.查询工资\n2.查询身份\n3.退出\n>>>")
             if choose == '':
                 input('%s的工资是%s元'%(username, salary))
             elif choose == '':
                 if username == 'alex':
                     input('supper user')
                 elif username == 'yuanhao' or username == 'wupeiqi':
                     input('normal user')
                 else:
                     input('unkown user')
             elif choose == '' or choose == 'q':
                 flag = False
             else:
                 input("Error")

作业八