Detailed explanation of the three modes of regularity (greedy, reluctant and possessive)

This time I will bring you a detailed explanation of the three modes of regularity (greedy, reluctant, and possessive), and Precautions for using the three modes of regularity (greedy, reluctant, and possessive) What are they? Here are actual cases. Let’s take a look.

Greediness (Greediness): Maximum matching

X?, X*, X+, X{n,} is the maximum matching. For example, if you want to use "<.+>" to match "aaava abb", maybe the result you expect is to match "", but the actual result will match Go to "aava .

In Greediness mode, it will try to match as wide a range as possible until the entire content is matched. At this time, when it is found that the match cannot be successful, it will start to shrink back a little. Matching range until successful match

String test = "a<tr>aava </tr>abb ";
String reg = "<.+>";
System.out.println(test.replaceAll(reg, "###"));

Output: a

abb

Reluctant(Laziness) (reluctant): minimum match

X??, X*?, X+?, X{n,}? is the minimum match. In fact, X{n, m}? and As long as the match is successful, no more attempts will be made to match a wider range of content

String test = "a<tr>aava </tr>abb ";
String reg = "<.+?>";
System.out.println(test.replaceAll(reg, "###"));

Output: a

aava

abb

Unlike Greediness, content is matched twice in Reluctant mode

Possessive (possessive): exact match

X?+,

#Possessive mode has a certain similarity with Greediness, that is, it tries to match the largest range of content until the end of the content, but unlike Greediness, full matching no longer falls back and tries to match a smaller range ##. #

String test = "a<tr>aava </tr>abb ";
String reg = "<.++>";
String test2 = "<tr>";
String reg2 = "<tr>";
System.out.println(test.replaceAll(reg, "###"));
System.out.println(test2.replaceAll(reg2, "###"));

Output: aaava abb

I believe you have mastered the method after reading the case in this article. Please pay attention to other related articles on the php Chinese website for more exciting information!

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