c# - Regex: Keep unkknown substring -

i try modify set of strings. need replace unknown parts keep unkknown middle part. in notepad++ used

as regex-input: .*(themeresource .*?brush).*

and regex-output: /1

with result:

input:

"<setter property="foreground" value="{themeresource systemcontrolforegroundbasehighbrush}" />" "<setter property="background" value="{themeresource systemcontrolbackgroundaltmediumlowbrush}" />" "<setter property="borderbrush" value="{themeresource systemcontrolforegroundbasemediumlowbrush}" />" "<discreteobjectkeyframe keytime="0" value="{themeresource systemcontrolpagebackgroundaltmediumbrush}" />" 

output:

"themeresource systemcontrolforegroundbasehighbrush" "themeresource systemcontrolbackgroundaltmediumlowbrush" "themeresource systemcontrolforegroundbasemediumlowbrush" "themeresource systemcontrolpagebackgroundaltmediumbrush" 

but c#-regex output allways: "/1"

i guess, there fundamental differences between c# , notepad++ regex, not understand change, since regex-input-selection seems work expected.

edit:

my code:

list<string> ls = file.readlines(@"c:\cbtemplate.xml").tolist().select(x=>regex.replace(x, ".*{(themeresource .*?brush).*", @"\1")); 

my notepad++ "find , replace":

to capturing group, use $1 instead of /1:

list<string> ls = file.readlines(@"c:\cbtemplate.xml").tolist().select(x=>regex.replace(x, ".*{(themeresource .*?brush).*", @"$1"));