在字符串文字前面加上“r”意味着什么？

Question

我第一次看到它在跨多行构建正则表达式时用作re.compile()的方法参数，因此我假设r代表RegEx

例如：

regex = re.compile(
    r'^[A-Z]'
    r'[A-Z0-9-]'
    r'[A-Z]$', re.IGNORECASE
)

那么r在这种情况下是什么意思呢？我们为什么需要它

Answer 1

r表示该字符串将被视为原始字符串，这意味着将忽略所有转义码

例如：

'\n'将被视为换行符，而r'\n'将被视为字符\，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 literal r"\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.

资料来源：Python string literals