learning_python_str_1
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字符串
- 字符串是一个包含若干个字符并按照一定顺序排列成整体的容器，支持
索引操作，字符串定义可以是"xxxx",'xxx',"""xxx""",'''xxx'''。
字符串的一些函数，函数较多，用分割线划分。
- 判断函数
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isalnum(self, *args, **kwargs): Return True if the string is an alpha-numeric 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.
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isalpha(self, *args, **kwargs): Return True if the string is an alphabetic string, False otherwise. A string is alphabetic if all characters in the string are alphabetic and there is at least one character in the string.
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isascii(self, *args, **kwargs): Return True if all characters in the string are ASCII, False otherwise. ASCII characters have code points in the range U+0000-U+007F. Empty string is ASCII too.
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isdecimal(self, *args, **kwargs): Return True if the string is a decimal 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.
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isdigit(self, *args, **kwargs): 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.
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isidentifier(self, *args, **kwargs): Return True if the string is a valid Python identifier, False otherwise. Use keyword.iskeyword() to test for reserved identifiers such as “def” and “class”.
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islower(self, *args, **kwargs): 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.
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isnumeric(self, *args, **kwargs): 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.
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isprintable(self, *args, **kwargs): Return True if the string is printable, False otherwise. A string is printable if all of its characters are considered printable in repr() or if it is empty.
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isspace(self, *args, **kwargs): Return True if the string is a whitespace string, False otherwise. A string is whitespace if all characters in the string are whitespace and there is at least one character in the string.
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istitle(self, *args, **kwargs): 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.
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isupper(self, *args, **kwargs): 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.
- 翻译
- isalpha(self, *args, **kwargs): 判断字符串是否全是字母。
- isalnum(self, *args, **kwargs): 判断字符串是否字母数字。
- isascii(self, *args, **kwargs): 判断字符串是否全是
ASCII字符。 - isdecimal(self, *args, **kwargs): 判断字符串是否全是数字。
- isdigit(self, *args, **kwargs): 判断字符串是否全是数字。
- isidentifier(self, *args, **kwargs): 判断字符串是否是有效的
python标识符。 - islower(self, *args, **kwargs): 判断字符串是否全是小写。
- isnumeric(self, *args, **kwargs): 判断字符串是否全是数字。
- isprintable(self, *args, **kwargs): 判断字符串是否是可打印的。
- isspace(self, *args, **kwargs): 判断字符串是否是空白字符。
- istitle(self, *args, **kwargs): 判断字符串是否是首字母大写，其他小写。
- isupper(self, *args, **kwargs): 判断字符串是否全是大写。
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- 格式转换函数
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strip(self, *args, **kwargs): Return a copy of the string with leading and trailing whitespace remove. If chars is given and not None, remove characters in chars instead.
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lstrip(self, *args, **kwargs): Return a copy of the string with leading whitespace removed. If chars is given and not None, remove characters in chars instead.
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rstrip(self, *args, **kwargs): Return a copy of the string with trailing whitespace removed. If chars is given and not None, remove characters in chars instead.
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ljust(self, *args, **kwargs): Return a left-justified string of length width. Padding is done using the specified fill character (default is a space).
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rjust(self, *args, **kwargs): Return a right-justified string of length width. Padding is done using the specified fill character (default is a space).
center(self, *args, **kwargs): Return a centered string of length width. Padding is done using the specified fill character (default is a space).
zfill(self, *args, **kwargs): Pad a numeric string with zeros on the left, to fill a field of the given width.The string is never truncated.
- 翻译
- strip(self, *args, **kwargs): 返回去掉字符串左右两侧空白字符或指定字符的拷贝。
- lstrip(self, *args, **kwargs): 返回去掉字符串左侧空白字符或指定字符的拷贝。
- rstrip(self, *args, **kwargs): 返回去掉字符串右侧空白字符或指定字符的拷贝。
- ljust(self, *args, **kwargs): 返回右侧用空格或指定字符补齐指定宽度的字符串。
- rjust(self, *args, **kwargs): 返回左侧用空格或指定字符补齐指定宽度的字符串。
- center(self, *args, **kwargs): 填充字符串左右两侧几乎相等的指定字符或空格，是字符串居于中间位置，返回这样的字符串。
- zfill(self, *args, **kwargs): 用
0在数字字符串的左边补齐给定的宽度，字符串不会truncated。
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- 查询函数
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find(self, sub, start=None, end=None): 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.
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rfind(self, sub, start=None, end=None): S.rfind(sub[, start[, end]]) -> int Return the highest 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.
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index(self, sub, start=None, end=None): 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 as in slice notation. Raises ValueError when the substring is not found.
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rindex(self, sub, start=None, end=None): S.rindex(sub[, start[, end]]) -> int Return the highest 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. Raises ValueError when the substring is not found.
- 翻译
- find(self, sub, start=None, end=None): 返回指定字符串在原字符串中出现的最小下标。若给定
start和end，则在指定范围里搜索；若指定字符串未发现，则返回-1。 - rfind(self, sub, start=None, end=None): 返回指定字符串在原字符串中出现的最大下标。若给定
start和end，则在指定范围里搜索；若指定字符串未发现，则返回-1。 - index(self, sub, start=None, end=None): 返回指定字符串在原字符串中出现的最小下标。若给定
start和end，则在指定范围里搜索；若指定字符串未发现，则抛出ValueError。 - rindex(self, sub, start=None, end=None): 返回指定字符串在原字符串中出现的最大下标。若给定
start和end，则在指定范围里搜索；若指定字符串未发现，则抛出ValueError。
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