Regular expression system tutorial (4)

4. operators with the same priority perform operations from left to right. operations with different priorities are first high, then low. The priority of various operators ranges from high to low: operator description escape character (),(? :),(?), [] Parentheses and square brackets SyntaxHighlighter. all (); 4. operation priority of various operators

Operations with the same priority are performed from left to right. operations with different priorities are first high and then low. The priorities of operators are as follows:

Operator	Description
	Escape character
(),(? :),(? =), []	Parentheses and square brackets
*, + ,?, {N}, {n ,}, {n, m}	Qualifier
^, $, Anymetacharacter	Location and order
|	"Or" operation