如何显示字典中列表中的成员 <int, List<string> &gt;？

Question

I have a Dictionary<int, List<string>> where the key is a paper code and the list is a list of students enrolled in the paper.

How do i display this list of students from a particular key ?

I have tried

Console.WriteLine(myDictionary[targetkey])

but i just get this back

System.Collections.Generic.List 1[System.String]`

Answer 1

myDictionary[targetkey] will return the List<string> at the given key and if you pass that to Console.WriteLine , it will just call .ToString() on it which will return System.Collections.Generic.List1[System.String] . Actually any object you pass to Console.WriteLine method, it will call ToString() on it.

If youYou need to iterate over your dictionary and then print each one out.

foreach(var thisList in myDictionary.Keys)
{
    foreach(var thisStudent in thisList)
    {
        Console.WriteLine(thisStudent);
    }
}

Answer 2

You can use TryGetValue to make sure the key is there. Then just loop through your List<string> .

var targetKey = 123;
List<string> students;

if(dictionary.TryGetValue(targetKey, out students))
    foreach(var student in students)
        Console.WriteLine(student);

Answer 3

You need to use for loop,

foreach (KeyValuePair<int, List<string>> dicItem in test)
{
   foreach (string entry in dicItem.Value)
   {
      Console.WriteLine("Current entry for list {0}: {1}", dicItem.Key, entry);
   }
}

Answer 4

Try

foreach ( var student in myDictionary[targetKey])
{
  Console.WriteLine(student);
}

Answer 5

myDictionary[targetkey] returns List<String> so Covert List<String> to string Array

Print result like below

if(myDictionary.ContainsKey(targetkey))
  Console.WriteLine(string.Join(",", myDictionary[targetkey].ToArray()));

Answer 6

Here is the solutions

    Dictionary<int, List<string>> dictionary = new Dictionary<int, List<string>>();
    List<string> students = new List<string>();
    //adding Elements to list
    students.Add("Raees Ul Islam");
    students.Add("Ubaid Ur Rehman");
    //adding item to dictionary
    dictionary.Add(1, students);
    //Retriveing Data from Dictionary..
    Console.WriteLine(((List<string>)dictionary[1])[0]);
    Console.WriteLine("---------------");
    //An Other Way to go through All Elements
    List<string> studentsRetrived = dictionary[1];

    foreach (var item in studentsRetrived)
    {
        Console.WriteLine(item);
    }
    Console.ReadLine();