CODEWITHSUNDEEP
c#
dlock
dlock

Reputation: 9577

Dictionary<string,Object> will not let me access the Object members

Considering:

Dictionary<string,Object> dict = new Dictionary<string,Object>();

dict.Add("Name","deadlock");
dict.Add("Birthday",new BD(12,12,1955));

Knowing that BD is:

public class BD {

public int Day {get; set; }
public int Month {get; set; }
public int Year {get; set;}

public BD(int x,int y,int z) { Day=x; Month=y; Year=z; }
}

My problem is that I can't reference Day,Month,Year from the dictionary like that:

int Day1 = dict["Birthday"].Day;

The above code won't work. Any suggestions are welcome.

Upvotes: 0

Views: 2043

Answers (4)

Gustavo Puma
Gustavo Puma

Reputation: 1055

You need to cast the object to the type you want to use:

int Day1 = ((BD) dict["Birthday"]).Day;

Upvotes: 1

John K
John K

Reputation: 28917

Although multiple data types are always in play on a variable or reference, the instance members are filtered through the eyes of only one data type (and what it inherited). Therefore the stated (declared) data type at a time. Then the compiler knows what data type of multiple it is dealing with at that point.

In your case any instance of BD is all of the types: BD and System.Object through inheritance. If any interfaces had been implemented then those would be additional data types that the instance is also.

However type Object only shows Object members (and what it inherited, which is nothing more) even if the data type BD is also part of it.

To explicitly state to the C# compiler your intention of what data type to use of multiple available, you will have to "downcast", cast and/or convert accordingly using one of the mechanisms in C#/.NET like: C# casting ((BD)dict["Birthday"]).Day;, explicit conversion between compatible reference types (dict["Birthday"] as BD).Day;. In the case of basic data types you can also use conversion e.g. System.Convert.ToInt32(myLongValue). More features exist in .NET to support conversion endeavours.

Upvotes: 1

Alan
Alan

Reputation: 46883

It doesn't work because dict["Birthday"] returns an Object of type Object

In order to use this as expected, you need to cast the object to an appropriate type.

if(dict["Birthday"] is BD)
{
  var bd = dict["Birthday"];
  bd.Day; //do something useful
}

//or
var bd = dict["Birthday"] as BD
if(bd != null)
{
  bd.Day; //something useful
}

However, what you are doing is a kludge. Collections are most effective when storing homogeneous types. By storing generic objects, you can certainly store mixed types, but you have the added responsibility of ensuring type safety before casting.

Upvotes: 1

user47589
user47589

Reputation: 

int Day1 = ((BD)dict["Birthday"]).Day;

You need to cast it into a BD object.

Upvotes: 4

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