How to: Convert from a STL/CLR Container to a .NET Collection

 

This topic shows how to convert STL/CLR containers to their equivalent .NET collections. As an example, we show how to convert a STL/CLR vector to a .NET ICollection<T> and how to convert a STL/CLR map to a .NET IDictionary<TKey, TValue>, but the procedure is similar for all collections and containers.

To create a collection from a container

  1. Use one of the following methods:

    • To convert part of a container, call the make_collection function, and pass the begin iterator and end iterator of the STL/CLR container to be copied into the .NET collection. This template function takes an STL/CLR iterator as a template argument. The first example demonstrates this method.

    • To convert an entire container, cast the container to an appropriate .NET collection interface or interface collection. The second example demonstrates this method.

Example

In this example, we create a STL/CLR vector and add 5 elements to it. Then, we create a .NET collection by calling the make_collection function. Finally, we display the contents of the newly created collection.

// cliext_convert_vector_to_icollection.cpp
// compile with: /clr

#include <cliext/adapter>
#include <cliext/vector>

using namespace cliext;
using namespace System;
using namespace System::Collections::Generic;

int main(array<System::String ^> ^args)
{
    cliext::vector<int> primeNumbersCont;
    primeNumbersCont.push_back(2);
    primeNumbersCont.push_back(3);
    primeNumbersCont.push_back(5);
    primeNumbersCont.push_back(7);
    primeNumbersCont.push_back(11);

    System::Collections::Generic::ICollection<int> ^iColl =
        make_collection<cliext::vector<int>::iterator>(
            primeNumbersCont.begin() + 1,
            primeNumbersCont.end() - 1);

    Console::WriteLine("The contents of the System::Collections::Generic::ICollection are:");
    for each (int i in iColl)
    {
        Console::WriteLine(i);
    }
}
The contents of the System::Collections::Generic::ICollection are:
3
5
7

Example

In this example, we create a STL/CLR map and add 5 elements to it. Then, we create a .NET IDictionary<TKey, TValue> and assign the map directly to it. Finally, we display the contents of the newly created collection.

// cliext_convert_map_to_idictionary.cpp
// compile with: /clr

#include <cliext/adapter>
#include <cliext/map>

using namespace cliext;
using namespace System;
using namespace System::Collections::Generic;

int main(array<System::String ^> ^args)
{
    cliext::map<float, int> ^aMap = gcnew cliext::map<float, int>;
    aMap->insert(cliext::make_pair<float, int>(42.0, 42));
    aMap->insert(cliext::make_pair<float, int>(13.0, 13));
    aMap->insert(cliext::make_pair<float, int>(74.0, 74));
    aMap->insert(cliext::make_pair<float, int>(22.0, 22));
    aMap->insert(cliext::make_pair<float, int>(0.0, 0));

    System::Collections::Generic::IDictionary<float, int> ^iDict = aMap;

    Console::WriteLine("The contents of the IDictionary are:");
    for each (KeyValuePair<float, int> ^kvp in iDict)
    {
        Console::WriteLine("Key: {0:F} Value: {1}", kvp->Key, kvp->Value);
    }
}
The contents of the IDictionary 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
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