正则表达式查找和删除具有特定模式的字符

Question

I have this string

This is mail@mail.text #1 but page is @001# 

_{(001 is variable, ex 01a or 021 etc)}

And I want to make it

This is mail@mail.text #1 but page is 001

With this ^@([0-9]{1,3})#\\z i can find a string that starts with "@" and ends with "#" with max 3 chars inside but it doesn't match inside a entire text.

Answer 1

You need to remove ^ (start of the string anchor) and replace the match with the contents of Group 1 using $1 backreference:

var str = "This is mail@mail.text #1 but page is @001#";
var result = Regex.Replace(str, @"@([0-9]{1,3})#\z", "$1");

See the regex demo

The @([0-9]{1,3})#\\z pattern will find @ , 1 to 3 digits (put inside a group), and then a # at the very end of string ( \\z ).

Another variation: if the value may start with a digit and can be followed with an ASCII letter or digit, use

var result = Regex.Replace(str, @"@([0-9][0-9a-zA-Z]{0,2})#\z", "$1");

And if the value can just be alphanumeric, just use

var result = Regex.Replace(str, @"@([0-9a-zA-Z]{1,3})#\z", "$1");