Python 字符串文字前面带有“r”是什么意思？
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What does preceding a string literal with "r" mean?
提问by Nikki Erwin Ramirez
I first saw it used in building regular expressions across multiple lines as a method argument to re.compile(), so I assumed that rstands for RegEx.
我第一次看到它用于跨多行构建正则表达式作为 的方法参数re.compile()，所以我认为它r代表 RegEx。
For example:
例如：
regex = re.compile(
r'^[A-Z]'
r'[A-Z0-9-]'
r'[A-Z]$', re.IGNORECASE
)
So what does rmean in this case? Why do we need it?
那么r在这种情况下是什么意思呢？为什么我们需要它？
采纳答案by Sebastian Paaske T?rholm
The rmeans that the string is to be treated as a raw string, which means all escape codes will be ignored.
这r意味着该字符串将被视为原始字符串，这意味着所有转义码都将被忽略。
For an example:
例如：
'\n'will be treated as a newline character, while r'\n'will be treated as the characters \followed by n.
'\n'将被视为换行符，而r'\n'将被视为\后跟n.
When an
'r'or'R'prefix is present, a character following a backslash is included in the string without change, and all backslashes are left in the string. For example, the string literalr"\n"consists of two characters: a backslash and a lowercase'n'. String quotes can be escaped with a backslash, but the backslash remains in the string; for example,r"\""is a valid string literal consisting of two characters: a backslash and a double quote;r"\"is not a valid string literal (even a raw string cannot end in an odd number of backslashes). Specifically, a raw string cannot end in a single backslash (since the backslash would escape the following quote character). Note also that a single backslash followed by a newline is interpreted as those two characters as part of the string, not as a line continuation.
当存在
'r'or'R'前缀时，反斜杠后面的字符将不加更改地包含在字符串中，并且所有反斜杠都保留在字符串中。例如，字符串文字r"\n"由两个字符组成：一个反斜杠和一个小写'n'。字符串引号可以用反斜杠转义，但反斜杠保留在字符串中；例如，r"\""是由两个字符组成的有效字符串文字：一个反斜杠和一个双引号；r"\"不是有效的字符串文字（即使是原始字符串也不能以奇数个反斜杠结尾）。具体来说，原始字符串不能以单个反斜杠结尾（因为反斜杠会转义后面的引号字符）。另请注意，单个反斜杠后跟换行符被解释为这两个字符作为字符串的一部分，而不是作为行的延续。
Source: Python string literals
来源：Python 字符串文字
回答by Nate
It means that escapes won't be translated. For example:
这意味着转义不会被翻译。例如：
r'\n'
is a string with a backslash followed by the letter n. (Without the rit would be a newline.)
是一个带有反斜杠后跟字母的字符串n。（没有r它，它将是一个换行符。）
bdoes stand for byte-string and is used in Python 3, where strings are Unicode by default. In Python 2.x strings were byte-strings by default and you'd use uto indicate Unicode.
b确实代表字节字符串，并在 Python 3 中使用，其中字符串默认为 Unicode。在 Python 2.x 中，默认情况下字符串是字节字符串，您可以u用来表示 Unicode。
