字符串是 Python 中最常用的数据类型，是以单引号'或双引号"括
起来的任意文本。我们可以使用引号('或")来创建字符串
#1.重复输出字符串
print('hellow'*2)
# 2. [] ,[:] 通过索引获取字符串中字符,这里和列表的
# 切片操作是相同的,具体内容见列表
print('helloworld'[2:])
# 3. in 成员运算符
# - 如果字符串中包含给定的字符返回 True
# 否则 False
print('e2l' in 'hello')
#列表里面
print(123 in [23,45,123])
#4. 格式字符串
print('Jayce is a good student')
print('%s is a good student '%'Jayce')
#5.+ 字符串的拼接
a='123'
b='abc'
c='456'
d1=a+b+c
print(d1)
# +效率低,该用join
# join(self, ab=None, pq=None, rs=None): # real signature unknown; restored from __doc__
# """
# Concatenate any number of strings.
#
# The string whose method is called is inserted in between each given string.
# The result is returned as a new string.
#
# Example: '.'.join(['ab', 'pq', 'rs']) -> 'ab.pq.rs'
# """
d2=''.join([a,b,c])
d3='***'.join([a,b,c])
print(d2)
print(d3)
#String的内置方法
str = "hellow Jayce {name} is {age}"
#count()统计元素个数
print(str.count("J"))
#capitalize()首字母大写
# capitalize(self, *args, **kwargs): # real signature unknown
# """
# Return a capitalized version of the string.
#
# More specifically, make the first character have upper case and the rest lower
# case.
# """
print(str.capitalize())
#center() 居中
# center(self, *args, **kwargs): # real signature unknown
# """
# Return a centered string of length width.
#
# Padding is done using the specified fill character (default is a space).
# """
print(str.center(30,'*'))
#endswith() 判断是否以某字符串结尾
# endswith(self, suffix, start=None, end=None): # real signature unknown; restored from __doc__
# """
# S.endswith(suffix[, start[, end]]) -> bool
#
# Return True if S ends with the specified suffix（后缀） False otherwise.
# With optional start, test S beginning at that position.
# With optional end, stop comparing S at that position.
# suffix can also be a tuple of strings to try.
# """
print(str.endswith('ce'))
#startswith() 判断是否以某字符串开头
# 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.
# With optional start, test S beginning at that position.
# With optional end, stop comparing S at that position.
# prefix can also be a tuple of strings to try.
# """
print(str.startswith('he'))
#expandtabs() 处加空格
# expandtabs(self, *args, **kwargs): # real signature unknown
# """
# Return a copy where all tab characters are expanded using spaces.
#
# If tabsize is not given, a tab size of 8 characters is assumed.
# """
print(str.expandtabs(tabsize=20))
#find() 查找一个元素，并返回其索引值
# 找不到返回 -1
# find(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
# """
# S.find(sub[, start[, end]]) -> int
#
# Return the lowest index in S where substring sub is found,
# such that sub is contained within S[start:end]. Optional
# arguments start and end are interpreted as in slice notation.
#
# Return -1 on failure.
# """
# return 0
print(str.find('J'))
#format()格式化输出
# format(self, *args, **kwargs): # known special case of str.format
# """
# S.format(*args, **kwargs) -> str
#
# Return a formatted version of S, using substitutions from args and kwargs.
# The substitutions are identified by braces ('{' and '}').
# """
print(str.format(name = '明铭',age = 23))
#format_map()
# format_map(self, mapping): # real signature unknown; restored from __doc__
# """
# S.format_map(mapping) -> str
#
# Return a formatted version of S, using substitutions from mapping.
# The substitutions are identified by braces ('{' and '}').
# """
# return ""
print(str.format_map({'name':'明铭','age':230}))
#index() 返回索引值，没有则报错
# index(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
# """
# S.index(sub[, start[, end]]) -> int
#
# Return the lowest index in S where substring sub is found,
# such that sub is contained within S[start:end]. Optional
# arguments start and end are interpreted理解 as in slice切片 notation记号，标记法.
#
# Raises ValueError when the substring is not found.
# """
# return 0
print(str.index('J'))
#isalnum()如果字符串所有字符都是文字、字母或数字则返回 True,否则返回 False
# isalnum(self, *args, **kwargs): # real signature unknown
# """
# Return True if the string is an alpha-numeric文字数的 string, False otherwise.
#
# A string is alpha-numeric if all characters in the string are alpha-numeric and
# there is at least one character in the string.
# """
print('abc123陈明铭'.isalnum()) #true
print('abc123&陈明铭'.isalnum()) #false
#isdecimal()如果字符串只包含十进制数字则返回 True 否则返回 False.
# isdecimal(self, *args, **kwargs): # real signature unknown
# """
# Return True if the string is a decimal十进位的，小数的 string, False otherwise.
#
# A string is a decimal string if all characters in the string are decimal and
# there is at least one character in the string.
# """
print('123456'.isdecimal())
print('a123456'.isdecimal())
#isnumeric()只包含数字字符，返回 True
# isnumeric(self, *args, **kwargs): # real signature unknown
# """
# Return True if the string is a numeric string, False otherwise.
#
# A string is numeric if all characters in the string are numeric and there is at
# least one character in the string.
# """
print('a123456'.isnumeric())
#isdigit()判断是否是整型数字
# isdigit(self, *args, **kwargs): # real signature unknown
# """
# Return True if the string is a digit string, False otherwise.
#
# A string is a digit string if all characters in the string are digits and there
# is at least one character in the string.
# """
print('123.456'.isdigit()) #False
#isidentifier()判断是否是有效的标识符
# isidentifier(self, *args, **kwargs): # real signature unknown
# """
# Return True if the string is a valid有效的 Python identifier, False otherwise.
#
# Use keyword.iskeyword() to test for reserved identifiers such as "def" and
# "class".
# """
print('123abc'.isidentifier())
print('abc'.isidentifier())
#islower() 判断是否全小写
# islower(self, *args, **kwargs): # real signature unknown
# """
# Return True if the string is a lowercase string, False otherwise.
#
# A string is lowercase if all cased characters in the string are lowercase and
# there is at least one cased character in the string.
# """
print('Abc'.islower())
#isupper()判断是否全大写
# isupper(self, *args, **kwargs): # real signature unknown
# """
# Return True if the string is an uppercase string, False otherwise.
#
# A string is uppercase if all cased characters in the string are uppercase and
# there is at least one cased character in the string.
# """
print('ABC'.isupper())
#isspace() 判断是否是空格
# isspace(self, *args, **kwargs): # real signature unknown
# """
# Return True if the string is a whitespace string, False otherwise.
#
# A string is whitespace空白符;空白字符;空格 if all characters in the string are whitespace and there
# is at least one character in the string.
# """
print(' '.isspace())
# #istitle() 判断是否识标题 （首字母大写）
# istitle(self, *args, **kwargs): # real signature unknown
# """
# Return True if the string is a title-cased string, False otherwise.
#
# In a title-cased string, upper- and title-case characters may only
# follow uncased characters and lowercase characters only cased ones.
# """
print(' Le Petit Prince'.istitle())
#lower()大写变小写
# lower(self, *args, **kwargs): # real signature unknown
# """ Return a copy of the string converted to lowercase. """
print(' Le Petit Prince'.lower())
#upper() 小写变大写
# upper(self, *args, **kwargs): # real signature unknown
# """ Return a copy of the string converted to uppercase. """
print(' Le Petit Prince'.upper())
#swapcase() 大写变小写，小写变大写
# swapcase(self, *args, **kwargs): # real signature unknown
# """ Convert uppercase characters to lowercase and lowercase characters to uppercase. """
print(' Le Petit Prince'.swapcase())
#ljust() 左对齐，返回长度宽度左对齐的字符串
# ljust(self, *args, **kwargs): # real signature unknown
# """
# Return a left-justified string of length width.
#
# Padding is done using the specified fill character (default is a space).
# """
print(' Le Petit Prince'.ljust(50,'*'))
#rjust()右对齐
# rjust(self, *args, **kwargs): # real signature unknown
# """
# Return a right-justified string of length width.
#
# Padding is done using the specified fill character (default is a space).
# """
print(' Le Petit Prince'.rjust(50,'*'))
#strip() 把 和 最左边和最右边的换行符 都去掉
# strip(self, *args, **kwargs): # real signature unknown
# """
# Return a copy of the string with leading and trailing whitespace remove.
#
# If chars is given and not None, remove characters in chars instead.
# """
print(' Le Petit Prince '.strip())
#rstrip()去右边
print(' Le Petit Prince '.rstrip())
#lstrip去左边
print(' Le Petit Prince '.lstrip())
print("冷大爷累了")
#string.replace(str1, str2, num=string.count(str1))
# 把 string 中的 str1 替换成 str2,如果 num 指定，则替换不超过 num 次
# replace(self, *args, **kwargs): # real signature unknown
# """
# Return a copy with all occurrences of substring old replaced by new.
#
# count
# Maximum number of occurrences to replace.
# -1 (the default value) means replace all occurrences.
#
# If the optional argument count is given, only the first count occurrences are
# replaced.
# """
print('Le Petit Prince Le Petit Prince'.replace('Le Petit Prince',"My Little Prince"))
print('Le Petit Prince Le Petit Prince'.replace('Le Petit Prince',"My Little Prince",1))
#rfind(str, beg=0,end=len(string) )
# 似于 find()函数，不过是从右边开始查找,依然从左数
print('Le Petit Prince'.rfind('P'))
#split(str="", num=string.count(str))
# 以 str 为分隔符切片字符串，如果 num有指定值，则仅分隔 num 个子字符串
# split(self, *args, **kwargs): # real signature unknown
# """
# Return a list of the words in the string, using sep as the delimiter定界符，分隔符 string.
#
# sep
# The delimiter according which to split the string.
# None (the default value) means split according to any whitespace,
# and discard empty strings from the result.
# maxsplit
# Maximum number of splits to do.
# -1 (the default value) means no limit.
# """
print('Le Petit Prince'.split(" "))
print('Le Petit Prince'.split("P"))#以字母P分割
# string.maketrans(intab, outtab])
# maketrans() 方法用于创建字符映射的转换表，对于接受两个
# 参数的最简单的调用方式，第一个参数是字符串，表示需要
# 转换的字符，第二个参数也是字符串表示转换的目标。
# max(str) 返回字符串 str 中最大的字母。
# min(str) 返回字符串 str 中最小的字母。
# string.partition(str)
# 有点像 find()和 split()的结合体,从 str 出现的第一个位置起,
# 把字符串 string 分 成 一 个 3 元 素 的 元 组
# (string_pre_str,str,string_post_str),
# 如果 string 中不包含str 则 string_pre_str == string.
# string.rpartition(str)似于 partition()函数,不过是从右边开始查找.
# string.decode(encoding='UTF-8', errors='strict')
# 以 encoding 指定的编码格式解码 string，如果出错默认报
# 一个 ValueError 的 异 常 ， 除 非 errors 指 定 的 是
# 'ignore' 或 者'replace'
# string.encode(encoding='UTF-8', errors='strict')
# 以 encoding 指定的编码格式编码 string，如果出错默认报
# 一个ValueError 的异常，除非 errors 指定的是'ignore'或者'replace'
# string.splitlines(num=string.count(' '))
# 按照行分隔，返回一个包含各行作为元素的列表，如果 num 指定，则仅切片 num 个行.