c#正则表达式——匹配非标准字符（使用转义序列）

string pattern = "1+";
            string input = "1+121";
            Regex regex = new Regex(pattern);
            MatchCollection matchCollection = regex.Matches(input);

            foreach (Match item in matchCollection)
            {
                Console.WriteLine(item.Value);
            }

            Console.WriteLine();
             pattern = "1n";//
             input = "1n+121";
             regex = new Regex(pattern);
             matchCollection = regex.Matches(input);

            foreach (Match item in matchCollection)
            {
                Console.WriteLine(item.Value);
            }


            Console.WriteLine();
            pattern = @"1+";//这里如果不加@会报错，加了@作为模式使用时并不是取消转义的作用，因为如果是取消转义，则认为是+，但是其实是+
            input = "1+121";
            regex = new Regex(pattern);
            matchCollection = regex.Matches(input);

            foreach (Match item in matchCollection)
            {
                Console.WriteLine(item.Value);
            }

输出：

1
1
1

1


1+