正则表达式语法
正则表达式语法
正则表达式是一种用于匹配字符串的模式在不同的编程语言中具有不同的语法。它可以用于文本搜索、文本替换、文本提取等各种操作。最初由美国计算机科学家Stephen Kleene提出现在已经成为计算机编程中不可缺少的一部分。
正则表达式语法主要包括以下几个部分：
字符集合
量词
分组
字符转义
字符集合是指匹配的字符集合可以是单个字符、多个字符组成的字符串、数字、空格等。量词则用于指定匹配的次数可以是单个字符匹配一次也可以是多个字符匹配多次如{1,3}表示匹配1到3次。
分组是指将一组字符作为一个整体进行匹配可以用括号将其包裹起来。字符转义是指将特殊字符转义成普通字符进行匹配这些特殊字符包括\、*、?、+等。
Regular Expression Syntax
A regular expression is a pattern used to match strings, with different syntax in different programming languages. It can be used for text search, text replace, text extraction and many other operations, initially proposed by American computer scientist Stephen Kleene, and now has become an indispensable part of computer programming.
The regular expression syntax mainly includes the following parts:
Character set
Quantifier
Group
Character escape
The character set refers to the set of characters that match, which can be a single character, a string of multiple characters, numbers, spaces, etc. The quantifier is used to specify the number of matches, which can be a single character match once, or multiple matches for multiple characters, such as {1,3} which means match 1 to 3 times.
Grouping refers to matching a group of characters as a whole, which can be enclosed in parentheses. Character escape refers to converting special characters into ordinary characters to match, including \, *, ?, + and other special characters.
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