Syntax for regular expressions in PHP

Three ways to write a delimiter:

Regexpal tool (positive regular expression debug tool):

The results can be displayed in real time.

Atomic:

Visible Atom, which is a character in the Uincode encoded table

Invisible atoms:

In order to avoid coding problems resulting in incorrect matching, to convert the text into Unicode encoding transcoding in the match , so there is no GBK\UTF encoding such as the mismatch problem.

How to filter the atoms of metacharacters:

|: or the meaning of

"": Indicates that any of the characters that appear inside will be matched. For example:

"^": match the inside of the atom, with "" instead, the format can only be so "^, change ^ position will change the meaning ." For example:

In addition to 789, the others are matched to!!!!

Multiple matches, with slices matching A-Z, A-Z, and 0-9.

Syntax for regular expressions in PHP