在c#中获取字符串的特定部分

string str = "Hello, World!";
string subStr = str.Substring(0, 5); // 结果为 "Hello"

string str = "Hello, World!";
string[] parts = str.Split(',');
string subStr = parts[0].Trim(); // 结果为 "Hello"

string str = "Hello, World!";
string pattern = @"\w+";
Match match = Regex.Match(str, pattern);
string subStr = match.Value; // 结果为 "Hello"