Grammar forms are defined in classification
A context-independent grammar consists of four elements:
A collection of terminologies, also known as lexical units.
A non-terminator set, also known as a syntax variable.
A generative set.
For grammar G = (V, T, S, P), if the form of the formula is as follows:
A-> XBA-> X
Where a and B belong to V, and X belongs to T *, which is called the right linear syntax. Similar, if the form of the formula is as follows:
A-> BXA-> X
Objective of this articleIn 30 minutes you will understand what the regular expression is and have some basic knowledge of it so that you can use it in your own program or Web page.
How to use this tutorial
Most importantly-please give me 30
Objective:Six months ago to the regular expression of interest, found a lot of information on the Internet, read a lot of tutorials, and finally in the use of a regular expression tool Regexbuddy to find his tutorial written very well, can be said
Basic Tutorials | tutorials | regular Expressions | regular
Objective of this article
How to use this tutorial
What exactly is a regular expression?
Testing Regular Expressions
A regular expression (Regular Expression) is a matching pattern that describes the characteristics of a string of text.
Just as the words "tall" and "strong" in natural language are abstracted out to describe things, regular expressions
The following content is mainly from Wikipedia.
Formal ScienceIt refers to the science of abstract forms, such as logic, mathematics, computing theory, information theory, and statistics.
The branch of mathematics and computer science that
Regular expressions usually contain alphabetic text (LiteralText) and metacharacters (metacharacter)The alphabetic text refers to normal text such as "ABCDE" to match any string containing "ABCDE".Metacharacters is more flexible in using common
What is a regular expressionRegular expressions are powerful tools for verifying and manipulating strings. A simple understanding of regular expressions can be thought of as a special validation string. The common use of regular expressions is to
The RegExp object provides a simple regular expression support feature.
Use of RegExp objects:
Copy Code code as follows:
Function regexptest (PATRN, STRNG)
Dim regEx, Match, matches ' Set variable.
Set regEx = New RegExp '
The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion;
products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the
content of the page makes you feel confusing, please write us an email, we will handle the problem
within 5 days after receiving your email.
If you find any instances of plagiarism from the community, please send an email to:
and provide relevant evidence. A staff member will contact you within 5 working days.