c# - Regular expression, match anything not enclosed in -

given string foobarbarbarfoobar, want have between foo. used expression , result is: barbarbar. it's working great.

(?<=foo).*(?=foo) 

now want opposite. given string foobarbarbarfoobar want not enclosed foo. tried following regular expression:

(?<!foo).*(?!foo) 

i expected bar result instead returns match foobarbarbarfoobar. doesn't make sense me. missing?

the explanation from: https://regex101.com/ looks me?

(?<!foo).*(?!foo) (?<!foo) negative lookbehind - assert impossible match regex below foo matches characters foo literally (case sensitive) .* matches character (except newline) quantifier: * between 0 , unlimited times, many times possible,    giving needed [greedy] (?!foo) negative lookahead - assert impossible match regex below foo matches characters foo literally (case sensitive) 

any appreciated

i'm hoping finds better approach, abomination may want: (.*)foo(?<=foo).*(?=foo)foo(.*)

the text before first foo in capture group 1 (with provided example empty) , after in capture group 2 (would 'bar' in case)

if want 'foo's included on either end, use instead: (.*)(?<=foo).*(?=foo)(.*). result in 'foo' in group 1, , 'foobar' in group 2.