c# - 从字符串中获取删除的字符

Question

我正在使用正则表达式从字符串中删除不需要的字符，如下所示:

str = System.Text.RegularExpressions.Regex.Replace(str, @"[^\u0020-\u007E]", "");

如何检索将被有效删除的不同字符？

编辑:

Sample input  : str         = "This☺ contains Åüsome æspecialæ characters"
Sample output : str         = "This contains some special characters"
                removedchar = "☺,Å,ü,æ"

Answer 1

string pattern = @"[\u0020-\u007E]";
Regex rgx = new Regex(pattern);
List<string> matches = new List<string> ();

foreach (Match match in rgx.Matches(str))
{
    if (!matches.Contains (match.Value))
    {
        matches.Add (match.Value);
    }
}