c# dictionary inside a list

Question

I need to use a dictionary inside this list

List<Dictionary<string, string>> People= new List<Dictionary<string, string>>();

So far I have tried to populate it with this

People[0] = new Dictionary<string, string>();
People[0].Add("ID number", "1");
People[0].Add("Name", "John");

and display it to the console

for (int i = 0; i < People.Count; i++)
{
    Console.WriteLine(People[i]["ID number"]);
    Console.WriteLine(People[i]["Name"]);
}

I got System.ArgumentOutOfRangeException error on run, any fixes?

You should consider creating a `Person` class instead of your current data structure. — Rand Random, Dec 12 '18 at 13:23
Collections of collections allways make me feel sceptic. I agree Rand you should create a class that represents that data-structure. — MakePeaceGreatAgain, Dec 12 '18 at 13:24
`People[0]` whereas your list is empty, of course it will throw an exception ..? To add item to a IList use Add method :`People.Add(...)` and yes this structure seems really weird :o — Florian, Dec 12 '18 at 13:26

haldo · Accepted Answer · 2018-12-12T13:36:21.727

3

You need to use Add to add items to a List in C#.

Change your code to:

    List<Dictionary<string, string>> People= new List<Dictionary<string, string>>();

    People.Add(new Dictionary<string, string>());
    People[0].Add("ID Number", "1");
    People[0].Add("Name", "John");
    for (int i = 0; i < People.Count; i++)
    {
        Console.WriteLine(People[i]["ID Number"]);
        Console.WriteLine(People[i]["Name"]);
    }

However, I'd recommend creating a class to represent Person:

public class Person 
{
    public string ID { get; set;}
    public string Name { get; set; }

    public Person(string id, string name)
    {
        ID = id;
        Name = name;
    }
}

And doing

var people = new List<Person>();
var person = new Person("1", "John");
people.Add(person);
for (int i = 0; i < people.Count; i++)
{
    Console.WriteLine(people[i].ID);
    Console.WriteLine(people[i].Name);
}

edited Dec 12 '18 at 13:36

answered Dec 12 '18 at 13:24

haldo

14,512
5
46
52

thanks a lot @haldo – Billy Anthony Dec 12 '18 at 13:27
1

@FakeCaleb thanks, updated now :) – haldo Dec 12 '18 at 13:31
@Florian - no cheating, let him fix it himself :) – Rand Random Dec 12 '18 at 13:32
1

@RandRandom oopsie! maybe you can replace `List` by `var` since you assign a `new List` this is pretty clear and lowercase `P` of `People`:p – Florian Dec 12 '18 at 13:35
1

@Florian - don't get picky now :D – Rand Random Dec 12 '18 at 13:36

score 1 · Answer 2 · edited Dec 12 '18 at 13:29

1

People.Add(new Dictionary<string, string>());

Don´t you need to add the first entry in the List first?

edited Dec 12 '18 at 13:29

Rand Random

7,300
10
40
88

answered Dec 12 '18 at 13:25

GrabnaMax

47
7

score 1 · Answer 3 · answered Dec 12 '18 at 13:26

1

replace

People[0] = new Dictionary<string, string>();

with

People.Add(new Dictionary<string, string>());

You get a System.ArgumentOutOfRangeException because you access a not existing item.

answered Dec 12 '18 at 13:26

fubo

44,811
17
103
137

c# dictionary inside a list

3 Answers3