摘要： Character Classes一个character class表示一组用于匹配输入字符串的字符集合。[character_group](Positive character group.) Matches any character in the specified character group. 例如，[1ert]将会匹配这4个字符中的任何一个[^character_group](Negative character group.) Matches any character not in the specified character group.例如，[^1ert]将会匹配除这4 阅读全文