Regular expression system tutorial (4)_PHP tutorial

4. The operation priorities of various operators

The operations with the same priority are performed from left to right, and the operations with different priorities are performed from high to low. The precedence of various operators from high to low is as follows:

操作符	描述
	转义符
(), (?:), (?=), []	圆括号和方括号
*, +, ?, {n}, {n,}, {n,m}	限定符
^, $, anymetacharacter	位置和顺序
|	“或”操作

http://www.bkjia.com/PHPjc/532538.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/532538.htmlTechArticle4. Operation priorities of various operators. Those with the same priority are operated from left to right, and those with different priorities are The operation is high first and then low. The priorities of various operators from high to low are as follows: Operator Description...