Regex中的锚定

Question

1. 在Python正则表达式中，必须^or$ 只出现一次？在

2. 我试着把两条线

   ^(.*\|.*)$^.*$
   

   它不起作用。你怎么配 几行？

注意：我不是用Python编程，而是在我的编辑器gedit中使用Python风格的Regex。在

谢谢和问候！在

Answer 1

看看^{}。在

我引用：

When specified, the pattern character '^' matches at the beginning of the string and at the beginning of each line (immediately following each newline); and the pattern character '$' matches at the end of the string and at the end of each line (immediately preceding each newline).

By default, '^' matches only at the beginning of the string, and '$' only at the end of the string and immediately before the newline (if any) at the end of the string.

Answer 2

你必须使用re.多行（或者甚至雷多尔如果您更改regex，并且取决于您实际想要匹配/执行的操作）

re.MULTILINE

When specified, the pattern character '^' matches at the beginning of the string and at the beginning of each line (immediately following each newline); and the pattern character '$' matches at the end of the string and at the end of each line (immediately preceding each newline).

By default, '^' matches only at the beginning of the string, and '$' only at the end of the string and immediately before the newline (if any) at the end of the string.

http://docs.python.org/library/re.html

顺便说一句，你在用-^(.*\|.*)$^.*$-这不是一个很好的正则表达式！（忽略了一个事实，你有多个$和{}，这是问题的重点。）在

Answer 3

正如其他答案所说，您正在寻找re.MULTILINE，但即使这样，您的regex也无法工作。在

$匹配换行符之前的位置，^匹配行的开头，因此regex中间的$^永远不会匹配。例如：

>>> re.search("^(.*)$^.*$", multiline_string, re.M)    # won't match
>>> re.search("^(.*)$\n^.*$", multiline_string, re.M)  # will match
<_sre.SRE_Match object at 0xb7f3e5e0>

您需要一些东西来匹配$和^之间的行尾字符。在