E.g I want match the keword "3398" after "red" from the string "This is red with number 3398".
Using non-capturing group regex will help me sovle this problem.
(?<=red.*?)\d+
Ref: http://stackoverflow.com/questions/30667041/regex-replace-ignoring-non-capturing-group
C# Regex ignoring non-capturing group
原文：http://www.cnblogs.com/wushuaiyi/p/5354046.html