这里它使用纯LINQ作为单个表达式:

static string StringJoin(string sep, IEnumerable<string> strings) {
  return strings
    .Skip(1)
    .Aggregate(
       new StringBuilder().Append(strings.FirstOrDefault() ?? ""), 
       (sb, x) => sb.Append(sep).Append(x));
}

而且非常快!

您看过聚合扩展方法了吗?

var sa = (new[] { "yabba", "dabba", "doo" }).Aggregate((a,b) => a + "," + b);

我代码中的真实例子:

return selected.Select(query => query.Name).Aggregate((a, b) => a + ", " + b);

查询是一个具有Name属性的对象，该属性是一个字符串，我想要所选列表上所有查询的名称，用逗号分隔。

这里有很多选择。你可以使用LINQ和StringBuilder，这样你就可以得到这样的性能:

StringBuilder builder = new StringBuilder();
List<string> MyList = new List<string>() {"one","two","three"};

MyList.ForEach(w => builder.Append(builder.Length > 0 ? ", " + w : w));
return builder.ToString();

我总是使用扩展方法:

public static string JoinAsString<T>(this IEnumerable<T> input, string seperator)
{
    var ar = input.Select(i => i.ToString());
    return string.Join(seperator, ar);
}

StringBuilder vs Select & Aggregate case超过3000个元素的快速性能数据:

单元测试——持续时间(秒) LINQ_StringBuilder - 0.0036644 LINQ_Select。聚合- 1.8012535

    [TestMethod()]
    public void LINQ_StringBuilder()
    {
        IList<int> ints = new List<int>();
        for (int i = 0; i < 3000;i++ )
        {
            ints.Add(i);
        }
        StringBuilder idString = new StringBuilder();
        foreach (int id in ints)
        {
            idString.Append(id + ", ");
        }
    }
    [TestMethod()]
    public void LINQ_SELECT()
    {
        IList<int> ints = new List<int>();
        for (int i = 0; i < 3000; i++)
        {
            ints.Add(i);
        }
        string ids = ints.Select(query => query.ToString())
                         .Aggregate((a, b) => a + ", " + b);
    }