How to: Convert from a .NET Collection to a STL/CLR Container
This topic shows how to convert .NET collections to their equivalent STL/CLR containers. As an example we show how to convert a .NET List<T> to a STL/CLR vector and how to convert a .NET Dictionary<TKey, TValue> to a STL/CLR map, but the procedure is similar for all collections and containers.
To create a container from a collection
To convert an entire collection, create a STL/CLR container and pass the collection to the constructor.
The first example demonstrates this procedure.
-OR-
Create a generic STL/CLR container by creating a collection_adapter object. This template class takes a .NET collection interface as an argument. To verify which interfaces are supported, see collection_adapter (STL/CLR).
Copy the contents of the .NET collection to the container. This can be done by using a STL/CLR algorithm, or by iterating over the .NET collection and inserting a copy of each element into the STL/CLR container.
The second example demonstrates this procedure.
Example
In this example, we create a generic List<T> and add 5 elements to it. Then, we create a vector using the constructor that takes a IEnumerable<T> as an argument.
// cliext_convert_list_to_vector.cpp
// compile with: /clr
#include <cliext/adapter>
#include <cliext/algorithm>
#include <cliext/vector>
using namespace System;
using namespace System::Collections;
using namespace System::Collections::Generic;
int main(array<System::String ^> ^args)
{
List<int> ^primeNumbersColl = gcnew List<int>();
primeNumbersColl->Add(2);
primeNumbersColl->Add(3);
primeNumbersColl->Add(5);
primeNumbersColl->Add(7);
primeNumbersColl->Add(11);
cliext::vector<int> ^primeNumbersCont =
gcnew cliext::vector<int>(primeNumbersColl);
Console::WriteLine("The contents of the cliext::vector are:");
cliext::vector<int>::const_iterator it;
for (it = primeNumbersCont->begin(); it != primeNumbersCont->end(); it++)
{
Console::WriteLine(*it);
}
}
The contents of the cliext::vector are: 2 3 5 7 11
In this example, we create a generic Dictionary<TKey, TValue> and add 5 elements to it. Then, we create a collection_adapter to wrap the Dictionary<TKey, TValue> as a simple STL/CLR container. Finally, we create a map and copy the contents of the Dictionary<TKey, TValue> to the map by iterating over the collection_adapter. During this process, we create a new pair by using the make_pair function, and insert the new pair directly into the map.
// cliext_convert_dictionary_to_map.cpp
// compile with: /clr
#include <cliext/adapter>
#include <cliext/algorithm>
#include <cliext/map>
using namespace System;
using namespace System::Collections;
using namespace System::Collections::Generic;
int main(array<System::String ^> ^args)
{
System::Collections::Generic::Dictionary<float, int> ^dict =
gcnew System::Collections::Generic::Dictionary<float, int>();
dict->Add(42.0, 42);
dict->Add(13.0, 13);
dict->Add(74.0, 74);
dict->Add(22.0, 22);
dict->Add(0.0, 0);
cliext::collection_adapter<System::Collections::Generic::IDictionary<float, int>> dictAdapter(dict);
cliext::map<float, int> aMap;
for each (KeyValuePair<float, int> ^kvp in dictAdapter)
{
cliext::pair<float, int> aPair = cliext::make_pair(kvp->Key, kvp->Value);
aMap.insert(aPair);
}
Console::WriteLine("The contents of the cliext::map are:");
cliext::map<float, int>::const_iterator it;
for (it = aMap.begin(); it != aMap.end(); it++)
{
Console::WriteLine("Key: {0:F} Value: {1}", it->first, it->second);
}
}
The contents of the cliext::map are: Key: 0.00 Value: 0 Key: 13.00 Value: 13 Key: 22.00 Value: 22 Key: 42.00 Value: 42 Key: 74.00 Value: 74
See Also
Tasks
How to: Convert from a STL/CLR Container to a .NET Collection