Question :
I first saw it used in building regular expressions across multiple lines as a method argument to re.compile(), so I assumed that r stands for RegEx.
For example:
regex = re.compile(
r'^[A-Z]'
r'[A-Z0-9-]'
r'[A-Z]$', re.IGNORECASE
)
So what does r mean in this case? Why do we need it?
Answer #1:
The r means that the string is to be treated as a raw string, which means all escape codes will be ignored.
For an example:
'n' will be treated as a newline character, while r'n' will be treated as the characters followed by 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
