c# - 如何编辑列表中的重复项？

Question

我正在使用带有 cId(类(class) ID)和 cName(类(class)名称)的 DropDownList。但是，如果有重复的 cName，我想加入 startDate 和 cName。喜欢:$"cName ({startDate})"

这是我的列表的样子:

var list = new List<(int cId, string cName, string startDate)>
{
    (1, "Math", "1/12"),
    (2, "Music", "1/12"),
    (3, "English", "1/12"),
    (4, "English", "11/4"),
    (5, "Swedish", "1/12"),
    (6, "Russia", "1/12")
};

因为有两个 cName 用英文， startDate 应该加到它的字符串里，比如:

cId    cName
----   -----
 1   | "Math"
 2   | "Music"
 3   | "English (1/12)"
 4   | "English (11/4)"
 6   | "Swedish"
 7   | "Russia"

我的想法是:

如果列表中有任何重复的 cName，cName = $"cName ({startDate})"

编辑:

这是将列表添加到 DropDownList 的方式:

foreach (var item in list)
      {
           dplCourse.Items.Add(new ListItem(item.cId, item.cName));
      }

Answer 1

您需要遍历列表以找出哪些是重复项，并在将重复项添加到显示列表之前更改重复项的名称。

var list = new List<(int cId, string cName, string startDate)>
{
    (1, "Math", "1/12"),
    (2, "Music", "1/12"),
    (3, "English", "1/12"),
    (4, "English", "11/4"),
    (5, "Swedish", "1/12"),
    (6, "Russia", "1/12")
};

var duplicates = new HashSet<string>(
            list.GroupBy(x => x.cName) //Group the items by name
                .Where(g => g.Count() > 1) //Find groups with more than 1
                .Select(g => g.Key)); //Just add the names to the HashSet, not the group

foreach (var item in list)
{
     var displayName = item.cName
     if(duplicates.Contains(displayName))
     {
         displayName += $" ({item.startDate})";
     }
     dplCourse.Items.Add(new ListItem(item.cId, displayName));
}