在C＃winforms中用逗号连接变量

Question

所有这些代码都能正常运行。我的问题是对于Messagebox中的变量lTest，我如何显示用逗号连接的列表结果。

List<int> lNetworkIds = new List<int>();
Dictionary<DisplayDay, int> numDayOccurances = new Dictionary<DisplayDay, int>();

foreach (Proposal lDetail in this._Proposal.Details)
{
    if (!lNetworkIds.Contains(lDetail.NetworkId))
        lNetworkIds.Add(lDetail.NetworkId);
    if (!numDayOccurances.ContainsKey(lDetail.Day))
        numDayOccurances[lDetail.Day] = 0;
    numDayOccurances[lDetail.Day]++;
}

if (numDayOccurances.Count > 0)
{ 

    string lTest = "";
    foreach (DisplayDay myday in numDayOccurances.Keys)
    {

        lTest += myday.ToString();
    }

    MessageBox.Show(lTest);

}

Answer 1

而不是foreach，请使用：

string lTest = String.Join(",", numDayOccurances.Keys);

Answer 2

您将需要使用String.Join（）：http://msdn.microsoft.com/en-us/library/57a79xd0.aspx

Answer 3

试试这个：

var lTest = string.Join(", ", numDayOccurances.Select(e=>e.Key.ToString()));