Can I use a collection initializer for Dictionary<TKey, TValue> entries?

Question

I want to use a collection initializer for the next bit of code:

public Dictionary<int, string> GetNames() {     Dictionary<int, string> names = new Dictionary<int, string>();     names.Add(1, "Adam");     names.Add(2, "Bart");     names.Add(3, "Charlie");     return names; } 

So typically it should be something like:

return new Dictionary<int, string> {     1, "Adam",    2, "Bart"    ... 

But what is the correct syntax for this?

Answer 1

var names = new Dictionary<int, string> {   { 1, "Adam" },   { 2, "Bart" },   { 3, "Charlie" } }; 

Answer 2

The syntax is slightly different:

Dictionary<int, string> names = new Dictionary<int, string>() {     { 1, "Adam" },     { 2, "Bart" } } 

Note that you're effectively adding tuples of values.

As a sidenote: collection initializers contain arguments which are basically arguments to whatever Add() function that comes in handy with respect to compile-time type of argument. That is, if I have a collection:

class FooCollection : IEnumerable {     public void Add(int i) ...      public void Add(string s) ...      public void Add(double d) ... } 

the following code is perfectly legal:

var foos = new FooCollection() { 1, 2, 3.14, "Hello, world!" };