What are the types of regular expressions?

Regular expression types include basic regular expressions, extended regular expressions, comprehensive regular expressions, Perl-compatible regular expressions, Python regular expressions, etc. Detailed introduction: 1. Basic regular expression: also called basic regular expression or BRE, it is the simplest type of regular expression. It supports commonly used metacharacters and syntax, such as ., *, ,?, ^, $, etc., but does not support escape characters and special character classes; 2. Extended regular expressions: also called extended regular expressions or ERE, It is expanded on the basis of basic regular expressions and so on.

Operating system for this tutorial: Windows 10 system, Dell G3 computer.

Regular Expression (Regular Expression) is a powerful text processing tool that can be used for matching, searching, replacing and other operations. There are many types of regular expressions based on different classification methods. Here are some of the common types:

1. Basic Regular Expression: Also known as Basic Regular Expression or BRE, it is the simplest type of regular expression. It supports common metacharacters and syntax, such as ., *, ,?, ^, $, etc., but does not support escape characters and special character classes.

2. Extended Regular Expression: Also called extended regular expression or ERE, it is an extension of the basic regular expression. It supports more metacharacters and syntax, such as {n}, {n,}, {n,m}, \d, \D, \s, \S, etc. It also supports pipe symbols (|) and capturing groups.

3. Full Regular Expression: Also known as full regular expression or FREG, it is one of the most comprehensive regular expression types. It supports almost all regular expression syntax and features, including metacharacters, character classes, qualifiers, capturing groups, backreferences, etc. Comprehensive regular expressions are commonly used for complex text processing and pattern matching tasks.

4. Perl Compatible Regular Expression: Also known as PCRE, it is a regular expression type compatible with the Perl language. Perl is a popular programming language known for its powerful text processing capabilities. PCRE supports almost all Perl regular expression syntax and functions, including metacharacters, character classes, repetition times, capturing groups, backreferences, etc.

5. Python Regular Expression (Python Regular Expression): Similar to PCRE, Python regular expression also supports Perl-compatible regular expression syntax. It is one of the standard libraries in the Python language for processing text and pattern matching. Python regular expressions provide flexible matching and replacement functions that can handle various complex text patterns.

These are just some of the common regular expression types, there are actually many other variations and extensions. Different programming languages ​​and tools may support different regular expression types and syntax.

The above is the detailed content of What are the types of regular expressions?. For more information, please follow other related articles on the PHP Chinese website!