CODEWITHSUNDEEP
dictionaryc++-cli
Austin
Austin

Reputation: 457

C++/CLI Dictionary of Dictionaries

Is there a way to create a Dictionary of Dictionaries in C++ CLI? I was previously using a Dictionary of String,ArrayList pairs and found it useful to have my ArrayList converted to a Dictionary of String,CustomValueStruct pairs instead to make use of the key matching.

The code I had for the Dictionary of String,ArrayList pairs:

Dictionary<String^, ArrayList^> myDictionary = gcnew Dictionary<String^, ArrayList^>();

How can I convert this to use a Dictionary of Dictionaries?

The code I tried using, which doesn't compile is:

Dictionary<String^, Dictionary<String^, CustomValueStruct>> myDictionary = gcnew Dictionary<String^, Dictionary<String^, CustomValueStruct>>();

Where CustomValueStruct is just a custom struct in my code, which previously lived in the ArrayList.

The result of the attempted line is:

error C3225: generic type argument for 'TValue' cannot be 'System::Collections::Generic::Dictionary<TKey,TValue>', it must be a value type or a handle to a reference type

Upvotes: 0

Views: 5590

Answers (1)

&#208;аn
&#208;аn

Reputation: 10875

As the compiler said, you forgot a ^:

auto myDictionary = gcnew Dictionary<String^, Dictionary<String^, CustomValueStruct>^>();

Note that you need create a Dictionary<String^, CustomValueStruct> when adding items to myDictionary:

myDictionary.Add("Key", gcnew Dictionary<String^, CustomValueStruct>());

Finally, be sure you really want CustomValueStruct to be a value type; you're usually better off writing

ref class CustomRefClass { /* ... */ };

which in turn requires a ^ for the nested Dictionary:

 auto myDictionary = gcnew Dictionary<String^, Dictionary<String^, CustomRefClass^>^>();

Upvotes: 1

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