how to ignore a character in the regular expression

Question

I do not know how to ignore an item from the ER.

just need to get P1, but this returns /P1.

is possible to just ignore the bar?

$pattern = "#(/P[0-9])?#";

Answer 1

There are two options here:

• Exclude it from the group, P1 will be the contents in the capture group:

   $pattern = "#/(P[0-9])#"; 

• Use a lookbehind so that the / isn't even a part of the match, the entire match will be P1 :

   $pattern = "#(?<=/)P[0-9]#"; 

Note that I also removed the ? after your group because I don't think you actually want it, this makes the previous element optional so the regex (/P[0-9])? would match literal any string (it would match an empty string if /P[0-9] could not be matched).

Answer 2

使用preg_ *函数，您可以使用\\K技巧来重置比赛开始，例如：

$pattern = '~/\KP[0-9]~';