regex - 这个正则表达式有什么作用？

Question

这是来自 NHibernate 的自动映射配置的字符串。我想知道它有什么作用。

return string.Format("{0}_", Regex.Replace(member.Name, "([a-z](?=[A-Z])|[A-Z](?=[A-Z][a-z]))", "$1_").ToUpper());

Answer 1

好吧，让我们把它分解。

//This is the start
([a-z](?=[A-Z])|[A-Z](?=[A-Z][a-z]))

[a-z](?=[A-Z]) //this means to match one lower case a-z followed by an uppercase A-Z
| //or
[A-Z](?=[A-Z][a-z]) //One uppercase A-Z followed by one uppercase and one lowercase a-z

//The replace
$1_ //Replace the match with "the match plus underscore". 
//aBxx would become a_Bxx and ABcxx would be A_Bcxx