C Regular expression 120

ab\w[xyui]c

ab is constant.

w is limited to letters or numbers.

xyui] means to take one of x, y, u, i.

c is also constant.

There's a lot of it in this book. Just go buy a book.

In my understanding, regular expressions:

[\u4e00-\u9fa5]$ "

It is not possible to match any strings.

Because: [u4e00- u9fa5]$

in your $, which has been matched to the end of the string.

As a result, you add a space to match:

The end of the string is followed by a space.

itself does not exist.

Because even if a string ends with a Chinese character plus a space, then the position at the end corresponds to $, and it can no longer match the space.

Therefore, such a regular rule is logically unworkable.

If you are interested, you can take a look at my summary:

Crifan regular expression learning experience.

You can't post an address here, please search for the title with Google to find the address of the post).

That's right, it's dispensable.

Because the ID number of the first generation is fifteen, and the second generation is eighteen, although there are not many of the first generation, there are still a few people who are using it.

In addition, if you look at the whole regularity, if these three numbers are not dispensable, why do you have to divide them, directly add them up in the first 14, for: d w$ Isn't it better?

In addition, there is a w at the back, which means that it can be letters, numbers and underscores, but this is a bit inaccurate, because some ID numbers are directly followed by a question mark, W does not support question marks, and there may be problems when encountering such an ID number, so it should be changed to the following appearance to be more compatible:

d(\d)?[w\?]

There is a problem with this regular, it should be d( d)?w$ This can mean that the 3 digits can be without, and then the 15-digit ID card can be matched.

In fact, this is too simple.,Finally, you have to write a or something that can pass.,Commonly used ID card verification, for example.。

^\d$|^d$|^d(\d|x|x)) $ means that all three of the following can be:

15 digits.

18 digits.

17 digits + x

?- Match the preceding subexpression zero times or once, or indicate a non-greedy qualifier.

d?This will support 15-digit ID cards.

It's the dispensable meaning of the D paragraph in the back.

First of all, you need to understand that the regular code is in the form of a string in the text, and some characters of the string need to be escaped, for exampleAnd, of course, regex also need to be escaped (double escape), for example\w

Browser console input.

For example, the specific content of this regular is:$ to insert text (([w -

The specific match is:

Matchthis symbol.

Insert textNormal full matchingInsert textThese four Chinese characters.

Match the Chinese opening parentheses

([\w\-\In parentheses, there is a grouping, which will be discussed below.

Match the Chinese closing parentheses

Still match oneSymbol.

For the list 4 grouping.

The parentheses are only grouped and do not participate in any matching, and the parentheses are assigned to group 1 (i.e., in the replacement text

Represents a range of single matches, and the circled regulars correspond to the range of single-match characters.

RepresentationThe circled range may match 0-n times (Match 0-1 timesMatch 1-n times).

\wIndicates that English characters and numbers are matched.

indicates that the minus sign is matched

Indicates a match Indicates a match

Indicates a match ( Normal parentheses have the meaning of grouping, so they need to be escaped.

indicates a match) then the meaning is obvious, match "$ to insert the text (abc-+ and replace group 1 with the text below.

Directly on the chestnuts.

Demonstration example of the Liuyuan Relator.

The red mark is the content that is grouped in the text, and the yellow marker marks the grouped Hail Tomb in the replaced text.

The blue marks are the contents of the grouping that has been replaced.