Initialize dictionary without values in C#

Question

I would like to create dictionary with keys only. For example:

Dictionary <string, double> SmplDict= new Dictionary<string, double>();
SmplDict.Add("KeyOne");
SmplDict.Add("KeyTwo");

Of course, I can initialize with some predefined values, but this values will be overwritten, so I want only keys declared for now. I tried

SmpDict.Add("KeyOne", null)

but it did not work.

Answer 1

You can't put null value where double value is expected, as it is not a reference-type but a value-type:

Dictionary <string, double>

Instead, put 0:

SmpDict.Add("KeyOne", 0)

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On the other hand, if you want to keep put nulls, mark your double value as nullable:

Dictionary <string, double?>