Add keys/values to Dictionary at declaration

Question

Very easy today, I think. In C#, its:

Dictionary<String, String> dict = new Dictionary<string, string>() { { "", "" } };

But in vb, the following doesn't work.

Public dict As Dictionary(Of String, String) = New Dictionary(Of String, String) (("",""))

I'm pretty sure there's a way to add them at declaration, but I'm not sure how. And yes, I want to add them at declaration, not any other time. :) So hopefully it's possible. Thanks everyone.

I've also tried:

Public dict As Dictionary(Of String, String) = New Dictionary(Of String, String) ({"",""})

And...

Public dict As Dictionary(Of String, String) = New Dictionary(Of String, String) {("","")}

And...

Public dict As Dictionary(Of String, String) = New Dictionary(Of String, String) {{"",""}}

Darin Dimitrov · Accepted Answer · 2010-09-22T17:36:33.617

137

This is possible in VB.NET 10:

Dim dict = New Dictionary(Of Integer, String) From {{ 1, "Test1" }, { 2, "Test1" }}

Unfortunately IIRC VS 2008 uses VB.NET 9 compiler which doesn't support this syntax.

And for those that might be interested here's what happens behind the scenes (C#):

Dictionary<int, string> VB$t_ref$S0 = new Dictionary<int, string>();
VB$t_ref$S0.Add(1, "Test1");
VB$t_ref$S0.Add(2, "Test1");
Dictionary<int, string> dict = VB$t_ref$S0;

edited Sep 22 '10 at 17:36

answered Sep 22 '10 at 17:30

Darin Dimitrov

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fine! I wonder how that behaves, does it build the two dimensional array first, and then it copies to the dictionary? – vulkanino Sep 22 '10 at 17:34
Dern. So you're saying that since I'm using VS2008 I can't do it? That stinkies. – XstreamINsanity Sep 22 '10 at 17:43
3

Yeap, a bit stinky :-) Time to upgrade. – Darin Dimitrov Sep 22 '10 at 17:44
Is there any way to convert a two dimensional array to a dictionary? If so, I'll just do that. My goal is that I have ViewModes and each mode has a separate query. I wanted to iterate through the dictionary, add the key to a view mode combo box, and the value would be the query. Or something of the sort. Maybe I'll have to use a two-dimensional array. – XstreamINsanity Sep 22 '10 at 17:47
I ended up just making it a property and adding them in there. Don't know why I didn't think of it before. – XstreamINsanity Sep 22 '10 at 18:59
With how it works behind the scenes, does `VB$t_ref$S0` have the same scope as `dict`? is `VB$t_ref$S0` Garbage Collected immediately? What if `dict` was a public property? – Luke T O'Brien Mar 28 '17 at 11:06

score 17 · Answer 2 · edited Nov 24 '21 at 10:50

17

It is much the same, use the From keyword:

    Dim d As New Dictionary(Of String, String) From {{"", ""}}

However, this requires version 10 of the language, available in VS2010.

edited Nov 24 '21 at 10:50

Andreas

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answered Sep 22 '10 at 17:33

Hans Passant

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score 14 · Answer 3 · edited Nov 24 '21 at 10:54

Here's a cool translation: You can also have a Generic Dictionary of strings and string array.

C#:

private static readonly Dictionary<string, string[]> dics = new Dictionary<string, string[]>
{
    {"sizes", new string[]  {"small", "medium", "large"}},
    {"colors", new string[]  {"black", "red", "brown"}},
    {"shapes", new string[]  {"circle", "square"}}
};

VB:

Private Shared ReadOnly dics As New Dictionary(Of String, String()) From {
 {"sizes", New String() {"small", "medium", "large"}},
 {"colors", New String() {"black", "red", "brown"}},
 {"shapes", New String() {"circle", "square"}}}

Cool haa :)

score 1 · Answer 4 · answered Sep 22 '10 at 17:28

1

There's no constructor to take a KeyValuePair for a dictionary.

answered Sep 22 '10 at 17:28

vulkanino

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Add keys/values to Dictionary at declaration

4 Answers4