C# 使用C查找字符串中的4个序列号#

我有一个大字符串，我想在字符串中找到4个序列号。我怎么得到它

例如：

string a=@"I(1946) am a string and I have some character and number and some sign like 4412 but I must find 4 sequence numbers in this."

var regex = new Regex(@"\d{4}");            
string a=@"I(1946) am a string and I have some character and number and some sign like 4412 but I must find 4 sequence numbers in this.";
foreach(Match match in regex.Matches(a))
    Console.WriteLine(match.Value);

预期结果：“1946”和“4412”

string a=@"2015/10/13 is my birthday.I love this date1234!"

预期结果：“2015”和“1234”

string a=@"xx888xx88x9xx99x9999xx"

预期结果：“9999”

您可以这样做，例如：

string a=@"I(1946) am a string and I have some character and number and some sign like 4412 but I must find 4 sequence numbers in this."

var regex = new Regex(@"\d{4}");            
string a=@"I(1946) am a string and I have some character and number and some sign like 4412 but I must find 4 sequence numbers in this.";
foreach(Match match in regex.Matches(a))
    Console.WriteLine(match.Value);

实例：

输出：

1946
4412
2015
1234

---

12345

-输出是什么？@UlugbekUmirov mm。。。我忘了考虑这个条件谢谢你的帮助，这个代码工作得很好！我想我必须多读正则表达式x