inventory of regex anchors -

1. ^ is said to match one The beginning of the line , but it is correct after "\ n" , "\ r" or "\ r \ n" Does not match. It matches the beginning of a string, though. In what sense it matches the beginning of a line, and how it is different from \ A

2. $ It is said that the end of a line , but it is "\ n" , "\ r" or "\ r \ n ". It matches the end of a string, though. In what sense does it match the end of a line, and how is it different from \ z ? Unlike

3. \ z , \ z , "\ n" mail before If the account is at the end of the string, it seems that \ A and \ z are naturally occurring concepts, and \ z Why is it that weird one is that \ z and \ z are defined, and not on the other side? And, you want to use \ z ?

   Can you illustrate using the examples above? If there is a difference in languages ​​/ standards, then it will be helpful to list them.

   The difference is that ^ and $ Changes in anchors can be behavior. With multiline mode, ^ and $ anchors emphasize the beginning and ending of a line.

   Together with mode, ^ and $ emphasize the beginning and closing of the anchor string.

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   Most regex implementations have a multiline mode.

   With Ruby, Perl, or Javascript, it is defined with the m modifier like / pattern / m

   With the .net, do it within (? M) pattern, or RegexOptions.Multiline counting.

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   To answer your third question ...

   \ A - The match must be match at the beginning of the string.

   \ z - The end of the string or the end of the string should match before \ n .

   \ z - The string should end in match.

   These three are stable which are not affected by any modifier. I believe that \ A and \ z seem to be an inappropriate coupler, it does not make much sense to me, but in a case where you can has the previous line feed that you want to ignore, then \ z can be preferred.