如果您在.NET3.5+上，则可以使用LINQ。没有Regex（速度更快）的解决方案如下：

var strings = new List<string>() { "82&?", "82,9", "abse82,9>dpkg" };
var result = strings.Select(s =>
    String.Join("",
        s.Where(c => char.IsNumber(c) || c ==  , )
        .ToArray()) /* .ToArray() is not needed on .NET 4 */
    ).ToList();

它只选择数字或逗号字符。但给定字符串8,1aa1，它将返回,8.11。

另一种方法稍微慢一点，但它将采用8,1aa1中的,8,1，而不会采用8、a或a、a：

var strings = new List<string>() { "82&?887..2", "82,9", "abse82,9>dpkg" };
var result = strings.Select(s =>
    String.Join("",
        s.SkipWhile(c => !char.IsNumber(c))
        .TakeWhile(c => (char.IsNumber(c) || c ==  , ))
        .ToArray()
    )
).Where(s => char.IsNumber(s.LastOrDefault())).ToList();

用我得到的答案上给出的方法进行100000次迭代的测试（使用Stopwatch）：

Fn: BrunoLM (Method 1)
Ticks: 524999

Fn: BrunoLM (Method 2)
Ticks: 729460

Fn: Ahmad
Ticks: 1323366

Fn: Josh
Ticks: 3783158

1000~长度字符串的相同测试：

var strings = new List<string>() { "82&?887..2".PadRight(1000,  2 ), "82,9".PadRight(1000,  1 ), "abse82,9>dpkg".PadRight(1000,  f ) };

结果：

Fn: Ahmad
Ticks: 11911332

Fn: BrunoLM (Method 2)
Ticks: 28149495

Fn: Josh
Ticks: 213681541

进一步阅读：

• Regular Expression Matching Can Be Simple And Fast

^{regular expression and text size n}

使用以下模式：＜code＞d+（，d+）。

• d: matches digits from 0-9
• +: matches the pattern at least once, so d+ will match at least one digit
• (,d+)?: this indicates a group (using the parentheses) that matches the comma followed by digits and optionally matches it (due to the ? at the end of the group)

代码段：

string[] inputs = { "82&?", "82,9", "abse82,9>dpkg", "foobar" };
foreach (var input in inputs)
{
    Match m = Regex.Match(input, @"d+(,d+)?");
    if (m.Success)
    {
        Console.WriteLine(m.Value);
    }
    else
    {
        Console.WriteLine("No match!");
    }
}

如果你只是在寻找这些角色，并试图删除其他任何内容，你可以做以下操作

    var strings = new List<string>()
                    {
                        "82&?",
                        "82,9",
                        "abse82,9>dpkg"
                    };
    var reg = new Regex("[^0-9,]*", RegexOptions.None);
    var output = new List<string>();
    foreach(var str in strings)
    {
        output.Add(reg.Replace(str, ""));
    }