通过正则表达式把给定字符串中的十六进制转换成十进制

    string str = this.textBox1.Text;
            Regex regex = new Regex("0[xX][0-9a-fA-F]{2,5}");
            MatchCollection mc = regex.Matches(str);
            foreach (Match m in mc)
            {
                str = str.Replace(m.Value, Convert.ToInt32(m.Value, 16) + "");
            }
            this.textBox1.Text = str;