


What are metacharacters in PHP? How do we use regular expression metacharacters? (with code)
The previous article introduced you to "What are atoms in regular expressions in PHP? What content does it consist of? (Attached code) ", this article continues to introduce to you what are metacharacters in PHP? How do we use regular expression metacharacters? (Attached code)
Metacharacter (atom modifier)
Atom number modifier
means that the previous atom appears - times or multiple times
? means that the previous atom appears e times or 1 time
* Indicates that the previous atom appears B times once or multiple times
{m,n} indicates that the previous atom appears at least H times and at most N times
-
{} means that the previous atom appears a specified number of times
{m,} means that the previous atom appears at least times or more
word boundary Modifiers (understand)
What is a word boundary
The characters that can divide a word are all included in word boundaries Spaces, tabs, special characters, the beginning and end of a string, the end of each line.
The parts that cannot be regarded as word boundaries are numbers, letters and_
- ##\bIndicates word boundaries
- \B represents non-word boundary
String boundary modifier (that is, the beginning and end)
- represents the content starting with the specified character
- $ represents the content ending with the specified character
- ^String $ represents an exact match It is an error if a certain string has one more or less one.
- If you want to use ^ and $ to match the beginning and end of each line, you need to use the pattern modifier m to treat it as multiple lines. .
Select modifier
Mode unit()
- 1 .Change priority
- #2. Treat multiple atoms as one atom for the purpose of using the atom number modifier.
- 3. Store the content matching the brackets into memory.
- 4. If you use () only to simulate an atom and use the atomic number modifier, you can use ?: at the beginning of the bracket to release the effect of storing it in memory. Improve efficiency.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
|
PHP Video Tutorial"
The above is the detailed content of What are metacharacters in PHP? How do we use regular expression metacharacters? (with code). For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics









